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The short answer
Most Nigerian banks publish a USSD code that blocks your account in seconds, usually ending in *911#: Access Bank's *901*911#, GTBank's *737*911# and Stanbic IBTC's *909*1*911# are examples. Some, like Access Bank, say the block stops all channels and works from any phone with your USSD PIN; others only deactivate USSD on your number. Lifting it normally needs a signed instruction, a call or a branch visit with ID.
When to freeze your own account
Block first and investigate later if:
- Your phone has been stolen or lost, with banking apps on it.
- You gave a PIN, OTP or password to someone who turned out to be a scammer.
- You see debits you did not make.
- Your SIM suddenly stopped working (a possible SIM swap).
- You installed a "support" app or screen-sharing tool at a caller's request.
Speed matters more than certainty. A block you did not need costs you a phone call to lift; a block you delayed can cost you the balance.
The block codes banks publish
From the banks' own pages as at October 2026 (Zenith from a 2019 report). Dial from your registered number unless the bank says otherwise.
| Bank | Code | What its page says it does |
|---|---|---|
| Access Bank | *901*911# | Blocks the account on all channels; works from any phone and needs your USSD PIN. Opting out of USSD through the menu disables USSD only |
| GTBank | *737*911# | Account block |
| Stanbic IBTC | *909*1*911# | Instant account block, validated by your PIN |
| Zenith Bank | *966*911# | Blocks the account where it is compromised or the card is lost (Investdata, 2019) |
| FirstBank | *894*911# | Deactivates your number on USSD, not the whole account |
Apps and fintechs
- Kuda: in the app, Profile Picture > Account Name > Block Account, which it says takes effect immediately. If your phone is gone, use selfhelp.kuda.com from another device, or call 0700022555832. The block is temporary and stops transfers, airtime, bills and other outgoing payments.
- Other apps: look for "freeze account", "block account" or "safety mode" in settings, and save the code or number somewhere outside your phone.
What a self-block does, and does not do
A self-requested block works like a Post No Debit you asked for. Money can usually still come in, but nothing goes out. It does not reverse money already taken: for that you need to report the fraud to your bank immediately, so it can contact the receiving bank. Our guide to the first hour after fraud sets out the order of steps.
Steps after a scam or lost phone
- Dial your bank's block code, or use the app on another device.
- Call the bank's official number and confirm the block covers all channels.
- Report any unauthorised debits in writing and ask for a reference number.
- Ask your network to block the SIM and issue a replacement; see phone stolen: protect your accounts.
- Change the password on the email linked to your bank.
- Report to the police and keep the report for your bank.
Lifting the block
Unblocking is deliberately harder than blocking, so a thief cannot undo it. Access Bank says you unblock with a signed instruction to its contact centre email, through its 24-hour contact centre, at a branch or through website self-service. Kuda asks you to request removal by email or in-app chat and verify your identity first. Expect to show ID, and to set a new PIN and password.
Before lifting the block, make sure the risk has gone: new SIM in hand, phone wiped or replaced, passwords changed.
Prepare now, before anything happens
- Write your bank's block code and contact number on paper and keep it in your wallet or at home.
- Save the number in a family member's phone too, so you can borrow theirs.
- Set a USSD PIN now if your bank needs one for the block code; Access Bank's *901*911#, for example, asks for it.
- Turn on fingerprint or face login and a screen lock on your phone.
- Note your account numbers somewhere safe, so you can quote them to the bank.
What the bank will ask when you call
Expect to confirm your name, account number, date of birth and recent transactions. Say clearly that you want the account blocked on all channels, not just the card, and ask the agent to confirm when it is done. Write down the time, the agent's name and any reference number. If money has already left, say so on the same call and ask the bank to start a fraud recall straight away.
If the scammer still has access
If someone has your app login or has installed a remote-access app on your phone, blocking the account is only the first step. Uninstall any app a caller asked you to install, change your banking password from a different device once the account is unblocked, and check that your phone number and email on the account have not been changed. If they have, tell the bank immediately.
Where Pryme fits
Pryme uses an authenticator app rather than SMS codes, plus a transaction PIN, so a stolen SIM alone is not enough to move money. If you think your Pryme account is at risk, contact us through the contact page; the security page explains the protections.
Questions people ask
What is the code to block my bank account?
It depends on the bank. Access Bank lists *901*911#, GTBank *737*911#, Stanbic IBTC *909*1*911# and Zenith *966*911#. FirstBank's *894*911# deactivates USSD on your number only.
Can I block my account from another phone?
Access Bank says its *901*911# block works from any phone with your USSD PIN. Many other codes need your registered number, so if your SIM is gone, call the bank or use another device to reach the app or self-help page.
Will blocking my account stop money already sent?
No. A block stops new outgoing payments. To try to recover money already taken, report the fraud to your bank at once so it can contact the receiving bank.
How do I unblock my account after blocking it?
Usually with a signed instruction, a call to the contact centre or a branch visit with ID. Fintechs such as Kuda ask you to verify your identity by email or chat.
Sources
- Access Bank: USSD Banking frequently asked questions · accessed Oct 2026
- GTBank: Bank 737 · accessed Oct 2026
- Stanbic IBTC: USSD banking · accessed Oct 2026
- Investdata: Zenith Bank unveils account blocking code *966*911# (7 Jan 2019) · accessed Oct 2026
- Kuda Help: Block your account (updated 13 Aug 2026) · accessed Oct 2026
- FirstBank: USSD banking · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.