HMRC Self Assessment Login: How to Sign In, Recover Your Details and Fix Common Errors

To log in to HMRC Self Assessment you sign in through GOV.UK with your Government Gateway user ID and password (or your GOV.UK One Login if HMRC has moved your account across), then enter a verification code from your phone. The sign-in page is the same for every HMRC service, so the trick is to have the right details to hand and to know which account Self Assessment is attached to. This guide walks through the sign-in, the recovery routes when something is missing, and the error messages people see most often.

Where to sign in

There are three doors into the same account:

• GOV.UK. Search for "sign in to your HMRC online account" and choose Self Assessment. Bookmark the page you land on rather than a search result, because look-alike sites advertise heavily around the January deadline.
• The HMRC app. Free on iPhone and Android. Once set up it can sign you in with your face, fingerprint or a six-digit PIN, and it shows your tax calculation, payments and UTR.
• Your personal tax account. If you already use the personal tax account for PAYE, Self Assessment appears as a tile once it is linked to the same Government Gateway ID.

Whichever door you use, you will not see Self Assessment until it has been added to your account. If you registered recently, that happens when you enter the activation code HMRC posts to you.

What you need before you log in

• Your Government Gateway user ID, which is 12 digits. HMRC sent it when you created the account. See our Government Gateway guide if you have never had one.
• Your password.
• The phone or authenticator app registered for two-step verification.
• Your Unique Taxpayer Reference (UTR), a 10-digit number, if you are enrolling Self Assessment for the first time. Our UTR guide explains where to find it.

Government Gateway or GOV.UK One Login?

HMRC has been moving its sign-in from Government Gateway to GOV.UK One Login, the single account being rolled out across government services. If your sign-in page asks for an email address rather than a 12-digit ID, you have already been moved. The two work the same way once you are in: One Login still uses a password and a security code, and your Self Assessment record is unchanged.

Do not create a new account just because the page looks different. A second account is the most common cause of "I can see my personal tax account but not my tax return". If in doubt, sign in with whichever details you used last year and follow the prompts.

Two-step verification

Every Self Assessment sign-in needs a second check. You can choose a text message, a voice call to a landline, or an authenticator app such as Google Authenticator or Microsoft Authenticator. The HMRC app can also approve a sign-in on your phone without a text at all, which is the most reliable option if you travel or change numbers.

You can change the method at any time from the security settings inside your account. If you have lost access to the phone, you will need to go through the recovery process below, so it is worth setting up a second method before you need it.

Lost your user ID or password?

On the sign-in page, choose "problems signing in". The options are:

• Forgotten user ID. HMRC emails it to the address on the account. You will be asked to confirm your identity, usually with your National Insurance number or UTR and details from a recent payslip, P60 or passport.
• Forgotten password. HMRC emails a reset link to the same address.
• No access to the email or phone. You can request that the user ID is posted to your home address, which takes up to ten working days. Allow for this before the 31 January deadline.

If you genuinely cannot recover the account, HMRC can create a new one and move your Self Assessment record to it, but this needs a phone call to the online services helpdesk and some patience.

Letting your accountant access your account

You never need to share your login with an accountant. Agents have their own agent services account, and you authorise them once. The quickest route is a digital handshake: your accountant sends a link, you sign in with your own details and approve the request. The older route is form 64-8, which HMRC processes by post. Once authorised, your accountant can view your statements, submit the return and speak to HMRC on your behalf, while your login stays private.

Common login errors and what they mean

• "You cannot access this service from your account." Self Assessment is not enrolled on this Government Gateway ID. Either you have a second account, or you still need to enter the activation code.
• "Your details do not match." The UTR or National Insurance number you typed does not match HMRC's record. Check for a transposed digit and try again; three failed attempts lock the service for a short period.
• "Activation code has expired." Codes last 28 days. Request a new one from inside your account.
• No verification text. The number on the account may be old. Use the voice call option or recover the account to update it.
• "Service unavailable." HMRC's systems are busiest in the last week of January and during evening maintenance windows. Try again in the morning rather than re-registering.

What Cloudkeepers can do

Most of our Self Assessment clients never log in at all. We hold agent authorisation, prepare the return from your records and send it to you for approval before filing, and we chase HMRC when an activation code or UTR goes missing. If you want the tax return taken off your plate, book a discovery call.

Related reading: how to register for Self Assessment, how to pay your tax bill and how to get your SA302.