Add your company and connect to HMRC
Enter your VAT registration number, choose your scheme, then authorise VATflow through HMRC’s own sign-in.
Last reviewed 13 October 2026
Before you start
- Your 9-digit VAT registration number (VRN), as shown on your VAT certificate.
- Your Government Gateway user ID and password for the business. If you do not have one, create it on GOV.UK first: HMRC online services (opens GOV.UK).
- The business must be signed up for Making Tax Digital for VAT with HMRC. Since April 2022 this applies to all VAT-registered businesses: check on GOV.UK.
- Your authenticator app, set up as described in Getting started.
Add the company
- Open Companies and choose Add Company.
- Enter the VRN without the GB prefix and without spaces.
- Enter the trading name as you want it to appear in VATflow.
- Choose the VAT scheme. Standard is the default. If the business is on the Flat Rate Scheme, choose Flat Rate and enter the percentage and the VAT registration date, because the first-year discount depends on it.
- Save. The company appears in Companies and in the switcher at the top of the page.
Connect to HMRC
VATflow never sees your Government Gateway password. The connection is made on HMRC’s own pages, and HMRC hands VATflow a token that lets it read and submit VAT returns for that one business.
- Open Companies and choose Connect HMRC next to the company. VATflow asks for your authenticator code first.
- You are taken to HMRC’s sign-in page. The address starts with www.tax.service.gov.uk. Sign in with the Government Gateway user ID and password for the business. HMRC may send you its own access code by text or app.
- HMRC shows an authority page that lists what VATflow will be able to do: view your VAT obligations and returns, and submit VAT returns. Choose Continue, or Give permission, to agree.
- HMRC sends you back to VATflow. The company now shows Connected.
The authority lasts for 18 months. VATflow shows a reconnect prompt when it is about to expire or if HMRC withdraws it. You can disconnect at any time from Companies, which deletes the token from VATflow.
Government Gateway or agent services?
A business connects with its own Government Gateway account. An accountant or bookkeeper who files for clients uses an HMRC agent services account instead, and each client must first authorise the agent with HMRC.
VATflow’s agent features are built but not yet switched on. Until then, file through the business’s own connection. See Accountants and agents for what is coming.
If the connection fails
- HMRC rejected our request: the token has expired or been withdrawn. Choose Reconnect HMRC and sign in again.
- The VRN is not found or not authorised: check the number against your VAT certificate, and check that the Government Gateway account you used is the one enrolled for this VAT registration.
- You were sent back to VATflow without a result: the sign-in took too long. Start again from Connect HMRC; each attempt is valid for 10 minutes.
- More codes and fixes are listed in Troubleshooting HMRC errors.