diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1da49d30..a836a65e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- New anonymous function `hasRegisteredSIK` for checking if a user has registered a SIK.
+
 ## [0.6.0] - 2023-11-28
 
 ### Added
diff --git a/src/services/anonymous.ts b/src/services/anonymous.ts
index a91dfd70..37ae8c08 100644
--- a/src/services/anonymous.ts
+++ b/src/services/anonymous.ts
@@ -79,9 +79,15 @@ export class AnonymousService extends Service implements AnonymousServicePropert
     );
   }
 
-  async fetchAccountSIK(address: string) {
+  async fetchAccountSIK(address: string): Promise<string> {
     invariant(this.url, 'No URL set');
-    return ZkAPI.sik(this.url, address);
+    return ZkAPI.sik(this.url, address).then((response) => response.sik);
+  }
+
+  async hasRegisteredSIK(address: string, signature: string, password?: string): Promise<boolean> {
+    return Promise.all([AnonymousService.calcSik(address, signature, password), this.fetchAccountSIK(address)])
+      .then(([calcSik, fetchSik]) => calcSik === fetchSik)
+      .catch(() => false);
   }
 
   async fetchZKProof(address: string) {
diff --git a/test/integration/zk.test.ts b/test/integration/zk.test.ts
index 1bac65e2..c6457b69 100644
--- a/test/integration/zk.test.ts
+++ b/test/integration/zk.test.ts
@@ -164,6 +164,59 @@ describe('zkSNARK test', () => {
         expect(votesLeftCount).toEqual(8); // The user voted twice
       });
   }, 285000);
+  it('should create an anonymous election, vote and check if the user has the SIK registered', async () => {
+    const census = new PlainCensus();
+    const voter = VocdoniSDKClient.generateWalletFromData('just dummy data' + Math.random());
+    census.add(voter.address);
+
+    const election = createElection(
+      census,
+      {
+        anonymous: true,
+      },
+      {
+        maxVoteOverwrites: 9,
+      }
+    );
+
+    let nullifier: string;
+    let signature: string;
+
+    await client.createAccount();
+
+    await client
+      .createElection(election)
+      .then((electionId) => {
+        expect(electionId).toMatch(/^[0-9a-fA-F]{64}$/);
+        client.setElectionId(electionId);
+        return client.fetchElection();
+      })
+      .then((publishedElection) => {
+        expect(publishedElection.electionType.anonymous).toBeTruthy();
+        return waitForElectionReady(client, publishedElection.id);
+      })
+      .then(async () => {
+        client.wallet = voter;
+        signature = await client.anonymousService.signSIKPayload(voter);
+
+        const vote = new AnonymousVote([0], signature, 'realpassword');
+        nullifier = await AnonymousService.calcVoteId(signature, 'realpassword', client.electionId);
+
+        const hasAlreadyVoted = await client.hasAlreadyVoted({ voteId: nullifier });
+        expect(hasAlreadyVoted).toBeFalsy();
+
+        return client.submitVote(vote);
+      })
+      .then(async (voteId) => {
+        expect(voteId).toEqual(nullifier);
+        const hasAlreadyVoted = await client.hasAlreadyVoted({ voteId });
+        expect(hasAlreadyVoted).toBeTruthy();
+        const votesLeftCount = await client.votesLeftCount({ voteId });
+        expect(votesLeftCount).toEqual(9);
+        expect(await client.anonymousService.hasRegisteredSIK(voter.address, signature, 'realpassword')).toBeTruthy();
+        expect(await client.anonymousService.hasRegisteredSIK(voter.address, signature, 'wrongpassword')).toBeFalsy();
+      });
+  }, 285000);
   it('should create a weighted anonymous election and vote successfully', async () => {
     const census = new WeightedCensus();
     const voter1 = Wallet.createRandom();