diff --git a/app/src/App.tsx b/app/src/App.tsx
index 8a959af..3705cb0 100644
--- a/app/src/App.tsx
+++ b/app/src/App.tsx
@@ -515,6 +515,37 @@ export default function App() {
       payoutHeadingRef.current?.focus();
     }
   }, [claimResult]);
+  
+  // When the claim step becomes available, pre-check each member's nullifier
+  // against `has_claimed` so we can mark ineligible members immediately
+  // (avoids generating a slow proof only to be rejected on-chain).
+  useEffect(() => {
+    let mounted = true;
+    async function checkEligibility() {
+      if (!fullyFunded || claimResult || !circleId || !admin) return;
+      try {
+        setBusy("Checking member eligibility…");
+        const client = await import("@sharibo/client");
+        const { computeExternalNullifier, computeNullifierHash, connect, hasClaimed } = client;
+        const external = await computeExternalNullifier(circleId, BigInt(round));
+        const adminClient = await connect(NETWORK, admin);
+        const results = await Promise.all(
+          members.map(async (m) => {
+            const nullifier = computeNullifierHash(m.identity.identityNullifier, external);
+            return await hasClaimed(adminClient, circleId, nullifier);
+          }),
+        );
+        if (!mounted) return;
+        setMembers((prev) => prev.map((m, i) => ({ ...m, ineligible: results[i], ineligibleReason: results[i] ? "Already claimed in this circle" : undefined })));
+      } catch (e) {
+        setError(toUiError(e));
+      } finally {
+        if (mounted) setBusy(null);
+      }
+    }
+    checkEligibility();
+    return () => { mounted = false; };
+  }, [fullyFunded, claimResult, circleId, round, admin]);
   // ────────────────────────────────────────────────────────────────────────
 
   // Every hook above must run on every render, so this check — which used to
@@ -576,6 +607,7 @@ export default function App() {
       identity: m.identity,
       funded: m.funded,
       fundHash: m.fundHash,
+      ineligible: m.ineligible ?? false,
     }));
     setMembers(loadedMembers);
     
@@ -618,6 +650,7 @@ export default function App() {
         keypair: Keypair.random(),
         identity: generateIdentity(),
         funded: false,
+        ineligible: false,
       }));
 
       const newTree = MerkleTree.create(
@@ -1059,15 +1092,16 @@ export default function App() {
               which one.
             </p>
             <div className="row">
-              {members.map((_, i) => (
+              {members.map((m, i) => (
                 <label key={i} className="radio">
                   <input
                     type="radio"
                     checked={claimantIndex === i}
                     onChange={() => setClaimantIndex(i)}
-                    disabled={!!busy}
+                    disabled={!!busy || !!m.ineligible}
+                    title={m.ineligible ? m.ineligibleReason ?? "Ineligible to claim" : undefined}
                   />
-                  member {i + 1}
+                  member {i + 1}{m.ineligible ? " (ineligible)" : ""}
                 </label>
               ))}
             </div>
diff --git a/app/src/components/ClaimSection.tsx b/app/src/components/ClaimSection.tsx
index bc8905f..c405081 100644
--- a/app/src/components/ClaimSection.tsx
+++ b/app/src/components/ClaimSection.tsx
@@ -21,15 +21,16 @@ export function ClaimSection({
         real member <em>without</em> revealing which one.
       </p>
       <div className="row">
-        {members.map((_, i) => (
+        {members.map((m, i) => (
           <label key={i} className="radio">
             <input
               type="radio"
               checked={claimantIndex === i}
               onChange={() => onSelectClaimant(i)}
-              disabled={!!busy}
+              disabled={!!busy || !!m.ineligible}
+              title={m.ineligible ? m.ineligibleReason ?? "Ineligible to claim" : undefined}
             />
-            member {i + 1}
+            member {i + 1}{m.ineligible ? ` (ineligible)` : ""}
           </label>
         ))}
       </div>
diff --git a/app/src/components/MemberRing.tsx b/app/src/components/MemberRing.tsx
index 86e21f4..3e0387f 100644
--- a/app/src/components/MemberRing.tsx
+++ b/app/src/components/MemberRing.tsx
@@ -2,11 +2,13 @@
 // as "the one that claimed" — that's the point. From outside the ring, all
 // five remain equally plausible; only the demo operator (via the radio
 // picker below) ever knows which one actually did.
+import type { Member } from "../types.js";
+
 export function MemberRing({
   members,
   revealed,
 }: {
-  members: { funded: boolean }[];
+  members: Member[];
   revealed: boolean;
 }) {
   const radius = 100;
@@ -21,10 +23,11 @@ export function MemberRing({
           return (
             <div
               key={i}
-              className={`ring-node ${m.funded ? "funded" : ""}`}
+              className={`ring-node ${m.funded ? "funded" : ""} ${m.ineligible ? "ineligible" : ""}`}
               style={{ transform: `translate(${x}px, ${y}px)` }}
+              aria-label={`member ${i + 1}${m.ineligible ? ", ineligible: already claimed" : ""}`}
             >
-              {i + 1}
+              {m.ineligible ? "×" : i + 1}
             </div>
           );
         })}
diff --git a/app/src/types.ts b/app/src/types.ts
index a269d26..4ff49c6 100644
--- a/app/src/types.ts
+++ b/app/src/types.ts
@@ -6,6 +6,8 @@ export interface Member {
   identity: Identity;
   funded: boolean;
   fundHash?: string;
+  ineligible?: boolean;
+  ineligibleReason?: string;
 }
 
 export interface ClaimResult {
diff --git a/packages/client/src/contract.ts b/packages/client/src/contract.ts
index 5fe4149..e838c07 100644
--- a/packages/client/src/contract.ts
+++ b/packages/client/src/contract.ts
@@ -246,10 +246,12 @@ export async function hasClaimed(
   circleId: bigint,
   nullifierHash: bigint,
 ): Promise<boolean> {
-  const tx = await withRetry(() => client.has_claimed({
+  // `has_claimed` is a pure read — don't submit or force a transaction.
+  // The SDK returns the raw result for read-only contract calls, so just
+  // invoke it and return the boolean directly.
+  const res = await withRetry(() => client.has_claimed({
     circle_id: circleId,
     nullifier_hash: nullifierHash,
   }));
-  const sent = await tx.signAndSend({ force: true });
-  return sent.result;
+  return res as boolean;
 }