HMRC Assist is a digital service from HMRC that helps you get your tax return right the first time. It reviews your quarterly updates along with other data HMRC holds, such as Pay As You Earn (PAYE) submissions made through Real Time Information (RTI).

After each quarterly update, when you run the HMRC tax calculation, HMRC Assist returns up to five personalised feedback messages. These can highlight missing income, such as undeclared rental income, or suggest tax reliefs or allowances you might qualify for. Each message can also include links to relevant guidance on gov.uk.

You can dismiss feedback messages once you’ve reviewed or actioned them. When you re-run the tax calculation, you may receive a new set of messages. These could include repeated messages if the advice still applies.

As the service evolves, HMRC plans to expand the types of feedback messages. This can increase the number of messages you receive when running a tax calculation.