How To Block Union Bank ATM Card: Step-By-Step Guide For 2025

How To Block Union Bank ATM Card: Losing your ATM card can be a stressful experience, especially when you think about the risk of someone accessing your money. Thankfully, Union Bank of Nigeria has made it simple for customers to block their ATM cards instantly using their mobile phones even without visiting the bank.

In this blog post, you’ll learn how to block your Union Bank ATM card using your phone, the USSD code, mobile app, SMS, or internet banking. You’ll also discover what to do after blocking your card, how to get a replacement, and answers to frequently asked questions about lost or stolen ATM cards.

Let’s get started

Also Read: Polaris Bank Transfer Code For Easy Banking In 2025/2026

How Can I Block My Union Bank ATM Card With My Phone

Blocking your card with your phone is one of the fastest ways to prevent any further unauthorised use without visiting a branch. Here are the main ways:

Dial USSD/Phone Code

If you are using the phone number registered with your Union Bank account, you can use a quick USSD code to block the card.

For example, Union Bank’s official social media indicates you can dial:*826*21# from your registered mobile number. *826*40# is also cited in a Union Bank tweet as a way to block your debit card.

So with your phone in hand:

• Dial the appropriate code (e.g., *826*21#) on the mobile that is registered with your bank account.
• Follow the prompt it may ask you to confirm which account/card, enter a PIN, or confirm you wish to block.
• Once done, you should receive a confirmation (via SMS or on-screen) that the card has been blocked.
• This method is great because it acts almost instantly, and can be done anywhere you have mobile phone access.

Use The Mobile Banking App

If you have the Union Bank mobile app installed (or any banking app that supports your account), you can block your card through the app:

• Open the app on your smartphone.
• Log in with your credentials (username/password or biometric, as applicable).
• Navigate to Card Services, Manage Cards, or similar. (Union Bank’s FAQ says: go to Self Service → Block/Unblock Debit Card. )
• Select the card you wish to block. Confirm the action.
• You should see a confirmation (or receive an SMS) that the card is now blocked.
• Using the app gives you additional visibility (see card details, see past transactions) and sometimes you can lock/unlock the card yourself without needing to call.

Call Customer Service

If for any reason you cannot use the USSD code or app (e.g., your phone is lost, your number isn’t registered, you don’t have internet), then a call to Union Bank’s customer service is the next safe step.

Ask to speak with the card-services or lost/stolen card department. They will verify your identity and block the card for you. According to the bank FAQs, one of the contact paths is to call: 01 271 6816 or 0700 700 7000.

Also Read: How To Activate Access Bank USSD Code (2025/2026 Guide)

What Is The code To Block Union Bank Card

Here’s is the code to block your Union bank Card Incase you misplaced it

• 82621# (dialed from your registered phone number) is referenced by Union Bank’s official posts.
• 82640# is another variant.
• Additionally, some blog sources mention a legacy SMS method: send “BLOCKCARD <your account number>” to 20123 from your registered number.

Important notes: Make sure you are dialing from the mobile number registered with your Union Bank account. If you use a different number, the code may not work or may be rejected.

Always follow the on-screen prompts carefully. After the code, you may be asked which card or account to block or to enter your PIN. After blocking, confirm via SMS or phone that the card is indeed blocked.

How Do I Block My Debit Card Through SMS

While USSD and app methods are more common now, SMS is still referenced for card blocking. For example: A blog article states: For Union Bank you can send “BLOCKCARD NUBAN” via SMS to 20123 using the phone number registered on your account.

However, Union Bank’s official FAQs do not currently mention SMS as a primary method — they emphasise Self Service online. So yes, you can try SMS if your mobile is registered and you know your account number (NUBAN).

• On your registered mobile number, open SMS.
• Type: BLOCKCARD <your 10-digit account number> and send it to 20123.
• Wait for a confirmation message. If you don’t receive one in short time, follow up via USSD or call the bank.
• After blocking, monitor your account for any strange transactions. Because SMS may be older/less prioritised, always verify via another channel (app or call) that the card is blocked.

How Can I Block My ATM Card With Another Phone

If you no longer have access to the registered phone number (e.g., your phone is lost/stolen) or you are using a different phone, you can still block your ATM card — but there are extra verification steps for security. Here’s what to do:

• Use any mobile phone (it doesn’t have to be the registered one) and call the Union Bank contact centre. Explain your card is lost/stolen and you cannot access your registered phone.
• The bank will ask you questions to verify your identity: account number, BVN (Bank Verification Number), date of birth, previous transactions etc. Be ready to answer accurately.
• Once verified, ask the agent to block the card on your behalf.
• Ask for confirmation (transaction number, SMS or email) that the card is blocked.
• Consider visiting a branch or using the app to issue a new card, and update your mobile number registration.
• Alternatively, if you know the USSD code (like 82621#) and your phone number is still active (even if it’s a different device), you might be able to dial the code. But if the number is no longer registered, it may not work—so the safer option is call the bank.

How Can I Block My Card Online

Yes, you can block your Union Bank ATM/debit card online via internet banking or mobile app. The process is straightforward:

• Visit the bank’s website or open the UnionOnline (Union Bank’s Internet Banking) or mobile banking app.
• Log in with your username and password (and any two-factor authentication if required).
• Navigate to: Self Service Block/Unblock Debit Card (as per Union Bank FAQ).
• Select the account/card you wish to block. Input your security word, token/OTP if prompted.
• Confirm and submit the request. You should get confirmation that the card has been blocked.
• After that, monitor your account to ensure no further unauthorised transactions appear.

Benefits Of Blocking Online:

• Done instantly from anywhere you have internet access.
• You can immediately see which card/account was blocked and any other cards you have.
• You avoid the queue at branches or phone waits.

How Can I Lock My Union Bank ATM Card

“Locking” the card often refers to a temporary freeze rather than full block (so you could still unlock later). With Union Bank: Through the mobile app or internet banking, you should find card-management options where you can block or unblock your card.

The FAQ uses “block/unblock debit card” language. If you believe the card is misplaced (not definitively lost), you may choose to lock (or block temporarily) via the app and then unlock once found.

Check the app to see if “lock/unlock” appears.If the option to just “lock” is not available, then blocking the card is the safe alternative. After the threat is resolved, you can reorder a new card.

If your card is at risk, block it. If you simply misplaced it and expect to find it soon, look for lock/unlock features in the app (if available) or call the bank and explain your preference.

Conclusion

Losing or misplacing your ATM/debit card can be stressful — but with the right steps, you can act quickly, regain control and minimise any potential loss. For customers of Union Bank of Nigeria, here are your go-to options:

• Use the USSD code (82621# or 82640#) from your registered mobile number
• .Use the mobile banking app or internet banking to block your card via self-service.
• Send an SMS (legacy method) to 20123 if your number is registered.
• Call customer service if you cannot access your registered phone or app.
• Monitor your account after blocking and request a replacement card if needed.
• Acting fast is the key: once you suspect your card is gone, do not delay.
• The sooner you block it, the less chance there is of unauthorised transactions.

Frequent Asked Questions – FAQs

What Do I Do If I Lost My Union Bank ATM Card

Immediately block the card using one of the methods above (USSD, app or call). Then go to a branch or app to request a replacement. Also review your account for unusual transactions and report them promptly.

What’s The Best Way To Report A Lost ATM

The best way is via the fastest channel you have access to — usually the USSD code from your registered phone, followed by the mobile app. These offer instant blocking. Then follow up with the bank in writing or at a branch if required.

Do I Need An Affidavit Of Loss For A Lost ATM Card

In most cases, you don’t need an affidavit just to block the card. Blocking can be done quickly via phone/app. An affidavit may be needed later if you want to claim for any losses, or request a card replacement depending on bank policy. Check with Union Bank’s branch for any local conditions.

What Info Is Needed To Block An ATM Card

You’ll typically need:

• Your account number or debit card number
• Identification to verify you are the account holder (BVN, date of birth, mobile number registered)
• The registered mobile number (for USSD/SMS)
• Access to online banking or mobile banking credentials if using app or internet method

Can I Still Withdraw Money If My Card Is Blocked

No, once a card is blocked, you cannot use that card at ATMs, POS or online for transactions. If you still need access to cash, you should request a replacement card or use a different access method (e.g., bank transfer, mobile app) where available.

Where Should I Get An Affidavit

If an affidavit is needed, you can go to a local notary public, Magistrate’s Court, or the legal department of your bank branch. Ensure it mentions the loss of your card and your account details.

Will Blocking Your Card Stop A Transaction

Blocking the card will stop new transactions from being authorised with that card number (ATM withdrawals, POS, online). However, if a transaction was already initiated and authorised before the block, it may still go through or settle depending on the timing. Always monitor your account and report any suspicious charge immediately.

Can Someone Withdraw Money With My Lost ATM card

Yes, if someone has your card and your PIN (or somehow overrides the PIN), they could withdraw money. That’s why you must block your card immediately when missing and monitor your account for unauthorised transactions.

What Are The Requirements For An Affidavit Of Loss

Typical requirements include:

• A written statement of the loss / theft / missing card
• Your name, account number, card number (if known)
• Details of when you noticed the card missing or used
• Signature, date
• Witness or notary signature, as per state legal requirements

For more information on How To Block Union Bank ATM Card, visit this post, https://www.unionbankng.com/support/faqs