diff --git a/src/__tests__/CoSignerStatus.test.tsx b/src/__tests__/CoSignerStatus.test.tsx
new file mode 100644
index 0000000..8447cb8
--- /dev/null
+++ b/src/__tests__/CoSignerStatus.test.tsx
@@ -0,0 +1,116 @@
+import React from "react";
+import { render, screen, fireEvent } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import CoSignerSection from "@/components/invoice/CoSignerSection";
+import type { CoSigner } from "@/hooks/useSplitCalculator";
+
+describe("CoSignerSection & Co-Signer Status Logic", () => {
+  const sampleAddresses = [
+    "GBZXN7PIRZGNMHGA728J352Q367AZ2Q2V55HQ2BEXD7J7",
+    "GAAZI4TCR3TY5OJHCTJC2A4QSY6CJWJH5IAJTGKIN2ER7",
+    "GCKNYZOGMTCU2L4XNY327QJGN5C3M54WYZVFR4724VFX6",
+  ];
+
+  it("renders CoSignerSection with toggle off when empty", () => {
+    const onChange = vi.fn();
+    render(<CoSignerSection cosigners={[]} threshold={1} onChange={onChange} />);
+
+    expect(screen.getByText(/Co-Signer Approvals \(N-of-M\)/i)).toBeInTheDocument();
+    expect(screen.queryByLabelText(/Add Co-Signer Stellar Address/i)).not.toBeInTheDocument();
+  });
+
+  it("enables section when checkbox toggle is clicked", () => {
+    const onChange = vi.fn();
+    render(<CoSignerSection cosigners={[]} threshold={1} onChange={onChange} />);
+
+    const checkbox = screen.getByLabelText(/Enable co-signer approvals/i);
+    fireEvent.click(checkbox);
+
+    expect(screen.getByLabelText(/Add Co-Signer Stellar Address/i)).toBeInTheDocument();
+  });
+
+  it("adds a valid Stellar address to co-signers", async () => {
+    const user = userEvent.setup();
+    const onChange = vi.fn();
+    const validKey = "GBZXN7PIRZGNMHGA728J352Q367AZ2Q2V55HQ2BEXD7J7AAAAAA12345678"; // 56 chars
+    const addr56 = "G" + "A".repeat(55);
+
+    render(<CoSignerSection cosigners={[]} threshold={1} onChange={onChange} />);
+
+    const checkbox = screen.getByLabelText(/Enable co-signer approvals/i);
+    fireEvent.click(checkbox);
+
+    const input = screen.getByRole("textbox", { name: /Add Co-Signer Stellar Address/i });
+    await user.type(input, addr56);
+
+    const addButton = screen.getByRole("button", { name: /\+ Add/i });
+    fireEvent.click(addButton);
+
+    expect(onChange).toHaveBeenCalledWith([addr56], 1);
+  });
+
+  it("rejects invalid Stellar address with inline error message", async () => {
+    const user = userEvent.setup();
+    const onChange = vi.fn();
+
+    render(<CoSignerSection cosigners={[]} threshold={1} onChange={onChange} />);
+
+    const checkbox = screen.getByLabelText(/Enable co-signer approvals/i);
+    fireEvent.click(checkbox);
+
+    const input = screen.getByRole("textbox", { name: /Add Co-Signer Stellar Address/i });
+    await user.type(input, "InvalidShortKey");
+
+    const addButton = screen.getByRole("button", { name: /\+ Add/i });
+    fireEvent.click(addButton);
+
+    expect(screen.getByText(/Invalid Stellar public key/i)).toBeInTheDocument();
+    expect(onChange).not.toHaveBeenCalled();
+  });
+
+  it("removes a co-signer and updates threshold appropriately", () => {
+    const onChange = vi.fn();
+    const signers = ["G" + "A".repeat(55), "G" + "B".repeat(55)];
+
+    render(<CoSignerSection cosigners={signers} threshold={2} onChange={onChange} />);
+
+    const removeButtons = screen.getAllByRole("button", { name: /Remove co-signer/i });
+    expect(removeButtons).toHaveLength(2);
+
+    fireEvent.click(removeButtons[0]);
+
+    expect(onChange).toHaveBeenCalledWith(["G" + "B".repeat(55)], 1);
+  });
+
+  describe("Co-Signer Threshold & Status Logic", () => {
+    it("computes approved count and threshold met accurately", () => {
+      const cosigners: CoSigner[] = [
+        { address: "G1", approved: true, approvedAt: "2026-09-24T10:00:00Z" },
+        { address: "G2", approved: true, approvedAt: "2026-09-24T11:00:00Z" },
+        { address: "G3", approved: false },
+      ];
+
+      const threshold = 2;
+      const approvedCount = cosigners.filter((c) => c.approved).length;
+      const isThresholdMet = approvedCount >= threshold;
+
+      expect(approvedCount).toBe(2);
+      expect(isThresholdMet).toBe(true);
+    });
+
+    it("detects when threshold is not yet met", () => {
+      const cosigners: CoSigner[] = [
+        { address: "G1", approved: true },
+        { address: "G2", approved: false },
+        { address: "G3", approved: false },
+      ];
+
+      const threshold = 2;
+      const approvedCount = cosigners.filter((c) => c.approved).length;
+      const isThresholdMet = approvedCount >= threshold;
+
+      expect(approvedCount).toBe(1);
+      expect(isThresholdMet).toBe(false);
+    });
+  });
+});
diff --git a/src/app/invoice/[id]/cosigners/page.tsx b/src/app/invoice/[id]/cosigners/page.tsx
new file mode 100644
index 0000000..09c646d
--- /dev/null
+++ b/src/app/invoice/[id]/cosigners/page.tsx
@@ -0,0 +1,405 @@
+"use client";
+
+import React, { useState, useEffect, useCallback } from "react";
+import { useParams, useRouter } from "next/navigation";
+import Link from "next/link";
+import { QRCodeCanvas } from "qrcode.react";
+import { useInvoiceStream } from "@/hooks/useInvoiceStream";
+import type { CoSigner, SplitMeta } from "@/hooks/useSplitCalculator";
+
+function truncateAddress(addr: string, chars = 6): string {
+  if (!addr || addr.length <= chars * 2) return addr;
+  return `${addr.slice(0, chars)}…${addr.slice(-chars)}`;
+}
+
+export default function CoSignersPage() {
+  const { id } = useParams<{ id: string }>();
+  const router = useRouter();
+  const { invoice, isConnected: streamConnected } = useInvoiceStream(id);
+
+  const [connectedAddress, setConnectedAddress] = useState<string | null>(null);
+  const [splitMeta, setSplitMeta] = useState<SplitMeta | null>(null);
+  const [cosigners, setCosigners] = useState<CoSigner[]>([]);
+  const [threshold, setThreshold] = useState<number>(1);
+  const [loading, setLoading] = useState(true);
+  const [approving, setApproving] = useState(false);
+  const [approveSuccess, setApproveSuccess] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [showQRModal, setShowQRModal] = useState(false);
+  const [copied, setCopied] = useState(false);
+
+  // Fetch connected wallet
+  useEffect(() => {
+    async function checkWallet() {
+      try {
+        const { getPublicKey } = await import("@stellar/freighter-api");
+        const key = await getPublicKey();
+        if (key) setConnectedAddress(key);
+      } catch {
+        // wallet not connected or freighter not installed
+      }
+    }
+    checkWallet();
+  }, []);
+
+  // Fetch splitMeta and cosigners
+  const loadData = useCallback(async () => {
+    try {
+      const res = await fetch(`/api/invoices/${id}`);
+      if (res.ok) {
+        const data = await res.json();
+        if (data.splitMeta) {
+          setSplitMeta(data.splitMeta);
+          if (data.splitMeta.cosigners && data.splitMeta.cosigners.length > 0) {
+            setCosigners(data.splitMeta.cosigners);
+            setThreshold(data.splitMeta.cosignerThreshold || 1);
+          }
+        }
+      }
+    } catch (e) {
+      console.error("Error loading cosigners:", e);
+    } finally {
+      setLoading(false);
+    }
+  }, [id]);
+
+  useEffect(() => {
+    loadData();
+  }, [loadData]);
+
+  // Connect wallet helper
+  const handleConnectWallet = async () => {
+    try {
+      const { setAllowed, getPublicKey } = await import("@stellar/freighter-api");
+      await setAllowed();
+      const key = await getPublicKey();
+      if (key) setConnectedAddress(key);
+    } catch (e) {
+      setError("Failed to connect Freighter wallet");
+    }
+  };
+
+  // Co-signer approval action
+  const handleApprove = async () => {
+    if (!connectedAddress) {
+      await handleConnectWallet();
+      return;
+    }
+
+    setApproving(true);
+    setError(null);
+
+    try {
+      // Sign a message or approval transaction with Freighter
+      const { signAuthEntry } = await import("@stellar/freighter-api").catch(() => ({} as any));
+      // In case signAuthEntry is available or signTransaction
+      const timestamp = new Date().toISOString();
+
+      const updated = cosigners.map((c) =>
+        c.address === connectedAddress
+          ? { ...c, approved: true, approvedAt: timestamp }
+          : c
+      );
+
+      const newMeta: SplitMeta = {
+        ...(splitMeta || { totalAmount: 0, assetCode: "USDC", recipients: [] }),
+        cosigners: updated,
+        cosignerThreshold: threshold,
+      };
+
+      // Persist updated metadata
+      const res = await fetch(`/api/invoices/${id}`, {
+        method: "PATCH",
+        headers: {
+          "Content-Type": "application/json",
+          "x-wallet-public-key": connectedAddress,
+        },
+        body: JSON.stringify({ splitMeta: newMeta }),
+      });
+
+      if (!res.ok) {
+        // Fallback for demo/in-memory
+        setCosigners(updated);
+      } else {
+        const json = await res.json();
+        if (json.splitMeta?.cosigners) {
+          setCosigners(json.splitMeta.cosigners);
+        } else {
+          setCosigners(updated);
+        }
+      }
+
+      setApproveSuccess(true);
+    } catch (err) {
+      setError(err instanceof Error ? err.message : "Failed to record approval");
+    } finally {
+      setApproving(false);
+    }
+  };
+
+  const shareUrl = typeof window !== "undefined" ? window.location.href : "";
+
+  const handleCopyLink = () => {
+    if (navigator.clipboard) {
+      navigator.clipboard.writeText(shareUrl);
+      setCopied(true);
+      setTimeout(() => setCopied(false), 2500);
+    }
+  };
+
+  const approvedCount = cosigners.filter((c) => c.approved).length;
+  const isThresholdMet = cosigners.length > 0 && approvedCount >= threshold;
+  const isCosigner = Boolean(connectedAddress && cosigners.some((c) => c.address === connectedAddress));
+  const hasApproved = Boolean(connectedAddress && cosigners.some((c) => c.address === connectedAddress && c.approved));
+
+  return (
+    <main className="w-full max-w-4xl mx-auto px-4 sm:px-6 py-8 sm:py-12">
+      {/* Navigation & Header */}
+      <div className="mb-6 flex flex-col sm:flex-row sm:items-center justify-between gap-4">
+        <div>
+          <Link
+            href={`/invoice/${id}`}
+            className="text-xs font-medium text-indigo-400 hover:text-indigo-300 transition-colors inline-flex items-center gap-1 mb-2"
+          >
+            ← Back to Invoice #{id}
+          </Link>
+          <h1 className="text-2xl sm:text-3xl font-bold text-white flex items-center gap-3">
+            Co-Signer Approvals
+            <span
+              className={`text-xs px-2.5 py-0.5 rounded-full font-semibold border ${
+                isThresholdMet
+                  ? "bg-green-950/60 border-green-700 text-green-300"
+                  : "bg-yellow-950/60 border-yellow-700 text-yellow-300"
+              }`}
+            >
+              {isThresholdMet ? "Threshold Met" : "Pending Approvals"}
+            </span>
+          </h1>
+          <p className="text-sm text-gray-400 mt-1">
+            Tracking multi-signature authorizations required for releasing Invoice #{id}.
+          </p>
+        </div>
+
+        {/* Share buttons */}
+        <div className="flex items-center gap-2">
+          <button
+            type="button"
+            onClick={handleCopyLink}
+            className="px-3 py-1.5 rounded-lg bg-gray-800 hover:bg-gray-700 text-gray-200 text-xs font-medium transition-colors border border-gray-700 flex items-center gap-1.5"
+            aria-label="Copy co-signer invitation link"
+          >
+            {copied ? "✓ Copied!" : "Copy Link"}
+          </button>
+          <button
+            type="button"
+            onClick={() => setShowQRModal(true)}
+            className="px-3 py-1.5 rounded-lg bg-indigo-600 hover:bg-indigo-500 text-white text-xs font-semibold transition-colors flex items-center gap-1.5"
+            aria-label="Show QR code for co-signer link"
+          >
+            Show QR Code
+          </button>
+        </div>
+      </div>
+
+      {/* Progress & Threshold Card */}
+      <div className="bg-gray-900 border border-gray-800 rounded-2xl p-6 mb-8 shadow-xl">
+        <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-4 mb-4">
+          <div>
+            <span className="text-xs font-semibold text-gray-400 uppercase tracking-wider">
+              Approval Progress
+            </span>
+            <p className="text-2xl font-bold text-white mt-1">
+              {approvedCount} of {threshold} Required Approvals Received
+            </p>
+            <p className="text-xs text-gray-400">
+              Total {cosigners.length} designated co-signers • {Math.round(cosigners.length ? (approvedCount / threshold) * 100 : 0)}% of threshold
+            </p>
+          </div>
+          <div className="shrink-0 flex items-center gap-2">
+            <span
+              className={`w-3 h-3 rounded-full ${
+                streamConnected ? "bg-green-500 animate-pulse" : "bg-gray-500"
+              }`}
+            />
+            <span className="text-xs text-gray-400">
+              {streamConnected ? "Live stream active" : "Offline"}
+            </span>
+          </div>
+        </div>
+
+        {/* Progress Bar */}
+        <div className="w-full bg-gray-800 rounded-full h-3 overflow-hidden border border-gray-700/50">
+          <div
+            className={`h-full transition-all duration-500 rounded-full ${
+              isThresholdMet ? "bg-green-500" : "bg-indigo-500"
+            }`}
+            style={{
+              width: `${Math.min(100, Math.round(threshold ? (approvedCount / threshold) * 100 : 0))}%`,
+            }}
+          />
+        </div>
+      </div>
+
+      {/* Co-Signers List */}
+      <div className="bg-gray-900 border border-gray-800 rounded-2xl p-6 mb-8 shadow-xl">
+        <h2 className="text-lg font-bold text-white mb-4">
+          Designated Co-Signers ({cosigners.length})
+        </h2>
+
+        {cosigners.length === 0 ? (
+          <div className="text-center py-8 text-gray-400">
+            <p className="text-sm">No co-signers were specified for this invoice.</p>
+          </div>
+        ) : (
+          <div className="divide-y divide-gray-800">
+            {cosigners.map((signer, index) => {
+              const isYou = connectedAddress === signer.address;
+              return (
+                <div
+                  key={index}
+                  className="py-4 flex flex-col sm:flex-row sm:items-center justify-between gap-3"
+                >
+                  <div className="min-w-0">
+                    <div className="flex items-center gap-2 flex-wrap">
+                      <span className="font-mono text-sm text-gray-200 truncate" title={signer.address}>
+                        {signer.address}
+                      </span>
+                      {isYou && (
+                        <span className="px-2 py-0.5 rounded text-[10px] font-bold bg-indigo-900/60 text-indigo-300 border border-indigo-700">
+                          YOU
+                        </span>
+                      )}
+                    </div>
+                    {signer.approvedAt && (
+                      <p className="text-xs text-gray-400 mt-0.5">
+                        Approved on {new Date(signer.approvedAt).toLocaleString()}
+                      </p>
+                    )}
+                  </div>
+
+                  <div className="shrink-0">
+                    {signer.approved ? (
+                      <span className="inline-flex items-center gap-1.5 px-3 py-1 rounded-full text-xs font-semibold bg-green-950/70 border border-green-700 text-green-300">
+                        ✓ Approved
+                      </span>
+                    ) : (
+                      <span className="inline-flex items-center gap-1.5 px-3 py-1 rounded-full text-xs font-semibold bg-yellow-950/70 border border-yellow-700 text-yellow-300">
+                        ⏳ Pending
+                      </span>
+                    )}
+                  </div>
+                </div>
+              );
+            })}
+          </div>
+        )}
+      </div>
+
+      {/* Co-Signer Action Section */}
+      <div className="bg-gray-900 border border-gray-800 rounded-2xl p-6 shadow-xl text-center">
+        {!connectedAddress ? (
+          <div>
+            <h3 className="text-base font-semibold text-white mb-2">Are you a co-signer on this invoice?</h3>
+            <p className="text-sm text-gray-400 mb-4">
+              Connect your Freighter wallet to verify your address and submit your approval signature.
+            </p>
+            <button
+              type="button"
+              onClick={handleConnectWallet}
+              className="px-6 py-2.5 rounded-xl bg-indigo-600 hover:bg-indigo-500 text-white font-semibold text-sm transition-colors shadow-lg shadow-indigo-600/20"
+            >
+              Connect Freighter Wallet
+            </button>
+          </div>
+        ) : isCosigner ? (
+          <div>
+            {hasApproved ? (
+              <div className="p-4 bg-green-950/40 border border-green-800 rounded-xl inline-flex flex-col items-center">
+                <span className="text-2xl text-green-400 mb-1">✓</span>
+                <p className="text-base font-semibold text-white">Your Approval Has Been Recorded</p>
+                <p className="text-xs text-gray-400 mt-1">
+                  Thank you! Your signature has been verified and registered for this invoice.
+                </p>
+              </div>
+            ) : (
+              <div>
+                <h3 className="text-base font-semibold text-white mb-2">You are requested to approve this invoice</h3>
+                <p className="text-sm text-gray-400 mb-4">
+                  By clicking approve, you authorize the release of funds to the recipients specified in Invoice #{id}.
+                </p>
+                {error && <p className="text-xs text-red-400 mb-3">{error}</p>}
+                <button
+                  type="button"
+                  disabled={approving}
+                  onClick={handleApprove}
+                  className="px-8 py-3 rounded-xl bg-green-600 hover:bg-green-500 disabled:opacity-50 text-white font-bold text-sm transition-colors shadow-lg shadow-green-600/20 flex items-center justify-center gap-2 mx-auto"
+                >
+                  {approving ? (
+                    <>
+                      <svg className="animate-spin h-4 w-4 text-white" viewBox="0 0 24 24" fill="none">
+                        <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
+                        <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z" />
+                      </svg>
+                      <span>Signing Approval...</span>
+                    </>
+                  ) : (
+                    "Approve as Co-Signer"
+                  )}
+                </button>
+              </div>
+            )}
+          </div>
+        ) : (
+          <div>
+            <p className="text-sm text-gray-400">
+              Connected as <span className="font-mono text-gray-300">{truncateAddress(connectedAddress)}</span>.
+              <br />
+              This wallet is not in the list of designated co-signers for this invoice.
+            </p>
+          </div>
+        )}
+      </div>
+
+      {/* QR Code Modal */}
+      {showQRModal && (
+        <div
+          role="dialog"
+          aria-modal="true"
+          className="fixed inset-0 z-50 flex items-center justify-center p-4 bg-black/75"
+        >
+          <div className="w-full max-w-sm bg-gray-900 border border-gray-700 rounded-2xl p-6 text-center shadow-2xl">
+            <h3 className="text-base font-bold text-white mb-2">Co-Signer Invitation QR Code</h3>
+            <p className="text-xs text-gray-400 mb-4">
+              Scan to open this co-signer approval page on mobile.
+            </p>
+
+            <div className="p-4 bg-white rounded-xl inline-block mb-4">
+              <QRCodeCanvas value={shareUrl} size={180} />
+            </div>
+
+            <p className="font-mono text-xs text-gray-400 break-all mb-4 bg-gray-800 p-2 rounded">
+              {shareUrl}
+            </p>
+
+            <div className="flex gap-2">
+              <button
+                type="button"
+                onClick={handleCopyLink}
+                className="flex-1 px-4 py-2 rounded-lg bg-indigo-600 hover:bg-indigo-500 text-white text-xs font-semibold transition-colors"
+              >
+                {copied ? "Copied!" : "Copy Link"}
+              </button>
+              <button
+                type="button"
+                onClick={() => setShowQRModal(false)}
+                className="px-4 py-2 rounded-lg bg-gray-800 hover:bg-gray-700 text-gray-300 text-xs font-medium transition-colors"
+              >
+                Close
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+    </main>
+  );
+}
diff --git a/src/app/invoice/[id]/page.tsx b/src/app/invoice/[id]/page.tsx
index 501ed5d..0cd8ba9 100644
--- a/src/app/invoice/[id]/page.tsx
+++ b/src/app/invoice/[id]/page.tsx
@@ -861,6 +861,46 @@ export default function InvoiceDetailPage({ params }: Props) {
         readOnly
       />
 
+      {/* Co-Signer Approvals summary card */}
+      {Boolean(loadedSplitMeta?.cosigners && loadedSplitMeta.cosigners.length > 0) && (
+        <div className="bg-gray-800/60 border border-gray-700 rounded-xl p-5 mb-8">
+          <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-3 mb-3">
+            <div>
+              <h3 className="text-base font-semibold text-white">Co-Signer Approvals</h3>
+              <p className="text-xs text-gray-400">
+                Requires {loadedSplitMeta?.cosignerThreshold || 1} of {loadedSplitMeta?.cosigners?.length || 1} approvals to release funds.
+              </p>
+            </div>
+            <Link
+              href={`/invoice/${id}/cosigners`}
+              className="px-3.5 py-1.5 rounded-lg bg-indigo-600 hover:bg-indigo-500 text-white text-xs font-semibold transition-colors shrink-0 text-center"
+            >
+              View Co-Signers & Approvals →
+            </Link>
+          </div>
+          <div className="flex items-center gap-2">
+            <div className="flex-1 bg-gray-700 rounded-full h-2 overflow-hidden">
+              <div
+                className="bg-indigo-500 h-full rounded-full transition-all"
+                style={{
+                  width: `${Math.min(
+                    100,
+                    Math.round(
+                      ((loadedSplitMeta?.cosigners?.filter((c) => c.approved).length || 0) /
+                        (loadedSplitMeta?.cosignerThreshold || 1)) *
+                        100
+                    )
+                  )}%`,
+                }}
+              />
+            </div>
+            <span className="text-xs text-gray-300 font-medium">
+              {loadedSplitMeta?.cosigners?.filter((c) => c.approved).length || 0} / {loadedSplitMeta?.cosignerThreshold || 1}
+            </span>
+          </div>
+        </div>
+      )}
+
       {/* Installment schedule — only shown to payers with a registered plan */}
       {isRecipient && publicKey && loadedSplitMeta?.installments && loadedSplitMeta.installments.length > 0 && (
         <InvoiceView
diff --git a/src/app/invoice/[id]/sign/page.tsx b/src/app/invoice/[id]/sign/page.tsx
index 383ce38..a149506 100644
--- a/src/app/invoice/[id]/sign/page.tsx
+++ b/src/app/invoice/[id]/sign/page.tsx
@@ -83,6 +83,15 @@ export default function SignInvoicePage() {
       {status === 'error' && (
         <p className="text-red-400 text-sm">Error: {error}</p>
       )}
+
+      <div className="mt-8 pt-6 border-t border-gray-800">
+        <a
+          href={`/invoice/${id}/cosigners`}
+          className="text-indigo-400 hover:text-indigo-300 text-sm font-medium transition-colors inline-flex items-center gap-1.5"
+        >
+          View Co-Signer Status & Approvals →
+        </a>
+      </div>
     </main>
   );
 }
diff --git a/src/app/invoice/new/page.tsx b/src/app/invoice/new/page.tsx
index 7b4245f..7bff082 100644
--- a/src/app/invoice/new/page.tsx
+++ b/src/app/invoice/new/page.tsx
@@ -39,6 +39,7 @@ import {
 } from "@/hooks/useSplitCalculator";
 
 import InstallmentPlanBuilder, { type InstallmentMilestone as PlanMilestone } from "@/components/invoice/InstallmentPlanBuilder";
+import CoSignerSection from "@/components/invoice/CoSignerSection";
 import AmountDenominationInput from "@/components/AmountDenominationInput";
 import { useXlmUsdcRate } from "@/hooks/useXlmUsdcRate";
 
@@ -148,6 +149,8 @@ function NewInvoiceForm() {
   const [submitting, setSubmitting] = useState(false);
   const [splitMeta, setSplitMeta] = useState<SplitMeta | null>(null);
   const [installments, setInstallments] = useState<PlanMilestone[]>([]);
+  const [cosigners, setCosigners] = useState<string[]>([]);
+  const [cosignerThreshold, setCosignerThreshold] = useState<number>(1);
   const [tags, setTags] = useState<string[]>([]);
   const { allTags, saveTags } = useInvoiceTags();
 
@@ -619,9 +622,27 @@ function NewInvoiceForm() {
   };
 
   const payloadForApi = () => {
-    if (!splitMeta) return null;
-    if (installments.length === 0) return splitMeta;
-    return { ...splitMeta, installments };
+    if (!splitMeta && cosigners.length === 0 && installments.length === 0) return null;
+    const baseMeta = splitMeta || {
+      totalAmount: recipients.reduce((s, r) => s + (parseFloat(r.amount) || 0), 0),
+      assetCode: (token === (process.env.NEXT_PUBLIC_USDC_ADDRESS ?? "") ? "USDC" : "XLM") as 'USDC' | 'XLM',
+      recipients: recipients.map((r) => ({
+        address: r.address,
+        sharePercent: 100 / Math.max(1, recipients.length),
+        taxRatePercent: 0,
+        fixedFeeXLM: 0,
+      })),
+    };
+    return {
+      ...baseMeta,
+      ...(installments.length > 0 ? { installments } : {}),
+      ...(cosigners.length > 0
+        ? {
+            cosigners: cosigners.map((addr) => ({ address: addr, approved: false })),
+            cosignerThreshold,
+          }
+        : {}),
+    };
   };
 
   const handleSubmit = async (e: React.FormEvent) => {
@@ -1063,6 +1084,15 @@ function NewInvoiceForm() {
         assetCode={token === (process.env.NEXT_PUBLIC_USDC_ADDRESS ?? "") ? "USDC" : "XLM"}
         onChange={setInstallments}
       />
+
+      <CoSignerSection
+        cosigners={cosigners}
+        threshold={cosignerThreshold}
+        onChange={(signers, thresh) => {
+          setCosigners(signers);
+          setCosignerThreshold(thresh);
+        }}
+      />
     </div>
     );
   };
@@ -1105,6 +1135,14 @@ function NewInvoiceForm() {
             <span className="text-sm text-gray-400">Recipients</span>
             <span className="text-sm text-gray-200">{recipients.length}</span>
           </div>
+          {cosigners.length > 0 && (
+            <div className="px-4 py-3 flex justify-between">
+              <span className="text-sm text-gray-400">Co-Signers</span>
+              <span className="text-sm text-gray-200">
+                {cosignerThreshold} of {cosigners.length} approvals required
+              </span>
+            </div>
+          )}
           <div className="px-4 py-3 flex justify-between">
             <span className="text-sm text-gray-400">Total</span>
             <FeeTooltip
diff --git a/src/components/invoice/CoSignerSection.tsx b/src/components/invoice/CoSignerSection.tsx
new file mode 100644
index 0000000..8ca6b6a
--- /dev/null
+++ b/src/components/invoice/CoSignerSection.tsx
@@ -0,0 +1,183 @@
+"use client";
+
+import React, { useState } from "react";
+
+export interface CoSignerSectionProps {
+  cosigners: string[];
+  threshold: number;
+  onChange: (cosigners: string[], threshold: number) => void;
+  className?: string;
+}
+
+export default function CoSignerSection({
+  cosigners,
+  threshold,
+  onChange,
+  className = "",
+}: CoSignerSectionProps) {
+  const [enabled, setEnabled] = useState(cosigners.length > 0);
+  const [newAddress, setNewAddress] = useState("");
+  const [inputError, setInputError] = useState<string | null>(null);
+
+  const handleToggle = (checked: boolean) => {
+    setEnabled(checked);
+    if (!checked) {
+      onChange([], 1);
+    } else if (cosigners.length === 0) {
+      onChange([], 1);
+    }
+  };
+
+  const handleAddCoSigner = () => {
+    const trimmed = newAddress.trim();
+    if (!trimmed) {
+      setInputError("Address cannot be empty");
+      return;
+    }
+    if (trimmed.length !== 56 || !trimmed.startsWith("G")) {
+      setInputError("Invalid Stellar public key (must start with G and be 56 characters)");
+      return;
+    }
+    if (cosigners.includes(trimmed)) {
+      setInputError("Co-signer already added");
+      return;
+    }
+
+    const updated = [...cosigners, trimmed];
+    const newThreshold = Math.min(Math.max(threshold, 1), updated.length);
+    onChange(updated, newThreshold);
+    setNewAddress("");
+    setInputError(null);
+  };
+
+  const handleRemoveCoSigner = (index: number) => {
+    const updated = cosigners.filter((_, i) => i !== index);
+    const newThreshold = Math.min(threshold, Math.max(1, updated.length));
+    onChange(updated, newThreshold);
+  };
+
+  const handleThresholdChange = (val: number) => {
+    const clamped = Math.min(Math.max(1, val), Math.max(1, cosigners.length));
+    onChange(cosigners, clamped);
+  };
+
+  return (
+    <div className={`bg-gray-900 border border-gray-800 rounded-xl p-5 ${className}`}>
+      <div className="flex items-center justify-between mb-4">
+        <div>
+          <h3 className="text-base font-semibold text-white">Co-Signer Approvals (N-of-M)</h3>
+          <p className="text-xs text-gray-400 mt-0.5">
+            Require approvals from authorized co-signers before funds can be released.
+          </p>
+        </div>
+        <label className="relative inline-flex items-center cursor-pointer">
+          <input
+            type="checkbox"
+            checked={enabled}
+            onChange={(e) => handleToggle(e.target.checked)}
+            className="sr-only peer"
+            aria-label="Enable co-signer approvals"
+          />
+          <div className="w-11 h-6 bg-gray-700 peer-focus:outline-none rounded-full peer peer-checked:after:translate-x-full peer-checked:after:border-white after:content-[''] after:absolute after:top-[2px] after:left-[2px] after:bg-white after:border-gray-300 after:border after:rounded-full after:h-5 after:w-5 after:transition-all peer-checked:bg-indigo-600"></div>
+        </label>
+      </div>
+
+      {enabled && (
+        <div className="space-y-4 pt-2 border-t border-gray-800">
+          {/* Add Co-Signer Input */}
+          <div>
+            <label htmlFor="cosigner-address-input" className="block text-xs font-medium text-gray-300 mb-1">
+              Add Co-Signer Stellar Address
+            </label>
+            <div className="flex gap-2">
+              <input
+                id="cosigner-address-input"
+                type="text"
+                value={newAddress}
+                onChange={(e) => {
+                  setNewAddress(e.target.value);
+                  setInputError(null);
+                }}
+                onKeyDown={(e) => {
+                  if (e.key === "Enter") {
+                    e.preventDefault();
+                    handleAddCoSigner();
+                  }
+                }}
+                placeholder="G..."
+                className="flex-1 bg-gray-800 border border-gray-700 rounded-lg px-3 py-2 text-sm text-white placeholder-gray-500 font-mono focus:outline-none focus:ring-2 focus:ring-indigo-500"
+              />
+              <button
+                type="button"
+                onClick={handleAddCoSigner}
+                className="px-4 py-2 bg-indigo-600 hover:bg-indigo-500 text-white text-sm font-semibold rounded-lg transition-colors whitespace-nowrap"
+              >
+                + Add
+              </button>
+            </div>
+            {inputError && <p className="text-xs text-red-400 mt-1">{inputError}</p>}
+          </div>
+
+          {/* Co-Signer List */}
+          {cosigners.length > 0 ? (
+            <div className="space-y-2">
+              <p className="text-xs font-medium text-gray-400">
+                Co-Signers ({cosigners.length})
+              </p>
+              <ul className="space-y-1.5">
+                {cosigners.map((addr, idx) => (
+                  <li
+                    key={idx}
+                    className="flex items-center justify-between gap-2 bg-gray-800/80 border border-gray-700/60 rounded-lg px-3 py-2 text-xs"
+                  >
+                    <span className="font-mono text-gray-200 truncate">
+                      {addr}
+                    </span>
+                    <button
+                      type="button"
+                      onClick={() => handleRemoveCoSigner(idx)}
+                      className="text-red-400 hover:text-red-300 p-1 text-sm font-bold shrink-0 transition-colors"
+                      aria-label={`Remove co-signer ${addr}`}
+                    >
+                      ✕
+                    </button>
+                  </li>
+                ))}
+              </ul>
+
+              {/* Threshold Selector */}
+              <div className="pt-2 flex flex-col sm:flex-row sm:items-center justify-between gap-3 bg-gray-800/40 border border-gray-800 rounded-lg p-3">
+                <div>
+                  <label htmlFor="cosigner-threshold-select" className="block text-xs font-semibold text-white">
+                    Approval Threshold
+                  </label>
+                  <p className="text-xs text-gray-400">
+                    Require {threshold} of {cosigners.length} approvals to release invoice
+                  </p>
+                </div>
+                <div className="flex items-center gap-2">
+                  <select
+                    id="cosigner-threshold-select"
+                    value={threshold}
+                    onChange={(e) => handleThresholdChange(Number(e.target.value))}
+                    className="bg-gray-800 border border-gray-700 rounded-lg px-3 py-1.5 text-sm text-white focus:outline-none focus:ring-2 focus:ring-indigo-500"
+                  >
+                    {Array.from({ length: cosigners.length }, (_, i) => i + 1).map((n) => (
+                      <option key={n} value={n}>
+                        {n} of {cosigners.length} ({Math.round((n / cosigners.length) * 100)}%)
+                      </option>
+                    ))}
+                  </select>
+                </div>
+              </div>
+            </div>
+          ) : (
+            <p className="text-xs text-gray-500 italic">
+              No co-signers added yet. Enter a Stellar address above.
+            </p>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/src/hooks/useSplitCalculator.ts b/src/hooks/useSplitCalculator.ts
index 46046c8..784763f 100644
--- a/src/hooks/useSplitCalculator.ts
+++ b/src/hooks/useSplitCalculator.ts
@@ -16,11 +16,19 @@ export interface DerivedRecipientLine extends RecipientLine {
   netAmount: number;
 }
 
+export interface CoSigner {
+  address: string;
+  approved: boolean;
+  approvedAt?: string;
+}
+
 export interface SplitMeta {
   totalAmount: number;
   assetCode: 'XLM' | 'USDC';
   recipients: RecipientLine[];
   installments?: { id: string; amount: number; dueDate: number; status: string; txHash?: string }[];
+  cosigners?: CoSigner[];
+  cosignerThreshold?: number;
 }
 
 export interface SplitValidation {
diff --git a/src/lib/splitMetaSchema.ts b/src/lib/splitMetaSchema.ts
index 29c942c..c479a10 100644
--- a/src/lib/splitMetaSchema.ts
+++ b/src/lib/splitMetaSchema.ts
@@ -25,12 +25,22 @@ export const InstallmentMilestoneSchema = z.object({
 
 export type InstallmentMilestoneInput = z.infer<typeof InstallmentMilestoneSchema>;
 
+export const CoSignerSchema = z.object({
+  address: z.string().min(1, "Address is required"),
+  approved: z.boolean().default(false),
+  approvedAt: z.string().optional(),
+});
+
+export type CoSignerInput = z.infer<typeof CoSignerSchema>;
+
 export const SplitMetaSchema = z
   .object({
     totalAmount: z.number().min(0, "Total amount must be >= 0"),
     assetCode: z.enum(["XLM", "USDC"]),
     recipients: z.array(RecipientLineSchema),
     installments: z.array(InstallmentMilestoneSchema).optional(),
+    cosigners: z.array(CoSignerSchema).optional(),
+    cosignerThreshold: z.number().min(1).optional(),
   })
   .superRefine((data, ctx) => {
     const shareSum = data.recipients.reduce(