Setting up a Government Gateway account to file Corporation Tax

Short version. To file your Corporation Tax return (the CT600) with HMRC, you need a Government Gateway account that is enrolled for Corporation Tax for that company. HMRC recommends a separate Government Gateway ID for each company you run. Setting one up is free, but HMRC posts an activation code to your registered office, which usually takes about ten working days, so start well before your filing deadline.

Why you need it

SimpleCompanyTax files your CT600 directly to HMRC using your own Government Gateway credentials. Those credentials must belong to an account that has Corporation Tax added (enrolled) for the exact company you are filing for. If you have never filed this company’s Corporation Tax online before, you will need to set that up first. We ask for the user ID and password only at the final step, use them once for that submission, and never store them.

A separate ID for each company

If you are a director of more than one company, HMRC recommends a separate Government Gateway ID for each company rather than adding several companies to one ID. Keeping them separate avoids any confusion at filing time about which company a set of credentials belongs to. So if you are setting this up for a second company, create a brand new Government Gateway ID for it using the steps below, even if you already have one for another company.

Create the account and add Corporation Tax

1. Go to gov.uk/log-in-register-hmrc-online-services, choose Sign in, then select “Create sign in details”.
2. Select No when asked if you are an agent.
3. Select Yes when asked if you are accessing services as a business or organisation.
4. Enter your email address (this is where your new Gateway user ID is sent), then give your name and set a password. Make a note of the user ID you are given.
5. Once you are signed in, choose the option to add Corporation Tax to the account.
6. Enter the company’s Unique Taxpayer Reference (UTR) and its Company Registration Number (or the registered office postcode).

The activation code

After the last step, HMRC posts an activation code to the company’s registered office address. This usually takes about ten working days. When it arrives, sign back in to the same Government Gateway ID and enter the code to activate (link) the Corporation Tax enrolment. You have 28 days to use the code before it expires. If it expires, you can request a new one from within the account.

Once the code is entered, the account is enrolled for Corporation Tax for that company, and you can file the CT600 with us using that user ID and password.

Finding your UTR

The UTR is a 10-digit number HMRC issues for the company’s Corporation Tax. HMRC posts it to the registered office shortly after the company is incorporated. You can also find it on HMRC Corporation Tax letters, or by signing in to the company’s Business Tax Account. It is not the same as your personal UTR, and it is not the company registration number.

Do this before your deadline

Because of the activation-code delay, do not leave this until the day your return is due. Set the account up, wait for the code, activate it, and confirm you can sign in and see Corporation Tax for the company. Then come to us to file.

If it is urgent and the activation code will not arrive in time, contact HMRC directly. They can sometimes provide a faster way to link your UTR to a Government Gateway ID.

This article is general guidance and HMRC’s own process can change, so follow the on-screen instructions at GOV.UK. Once your account is enrolled, see filing to HMRC, Companies House, or both for what happens next.