HMRC Assist Explained: What Submission Feedback Actually Does

There is a filter on HMRC's find-software service that almost nobody uses, because almost nobody knows what it means. It is called HMRC Assist (Submission Feedback), and it is one of the few features on that directory that changes what happens after you press submit rather than before.

In short: HMRC Assist compares what you have just submitted against the information HMRC already holds about you, and sends messages back into your software when something looks wrong. It is HMRC telling you about a likely error while you can still do something about it, rather than a letter about it eighteen months later.

As of the 5 August 2026 scrape of the directory, 28 of the 122 listed products support it and 94 do not.

What HMRC Assist actually is

HMRC describes Assist as a digital service designed to help customers get their tax return right first time. GOV.UK's software guidance puts it plainly: the feature "provides feedback and highlights errors for your tax return using: information in your submissions to HMRC; the data HMRC holds."

That second half is the important part. HMRC does not only look at what you sent. It looks at what it already knows about you from other sources, most obviously PAYE information reported by employers through Real Time Information. If your employer has told HMRC you earned £18,000 in the tax year and your final declaration says something materially different, that is precisely the kind of mismatch Assist is built to surface.

The service analyses information provided through quarterly updates alongside that held data, and returns tailored feedback messages. A message is only presented when HMRC identifies a potential error in the information provided and considers it necessary for you to review it, and the service returns a maximum of five messages per request. It is deliberately quiet.

How it works in practice

The mechanics are simple, and knowing them tells you what to expect from a product that advertises the feature.

Your software calls HMRC's Self Assessment Assist API to request a report, typically around a quarterly update or the final declaration. HMRC runs its checks and responds in one of two ways: with messages, when it has something to say, or with an empty response when it does not. Your software then shows you any messages it received.

Two consequences follow.

Silence is the normal case. Most submissions produce nothing. If you never see a message, that does not mean the feature is broken.

You will not see the messages anywhere else. HMRC is explicit that Assist messages are separate from the messages in your tax account, and can only be accessed through MTD-compatible software. If your product has not built the integration, the feedback is not sitting somewhere waiting for you. It is simply never generated.

That last point is what makes this a software-choice question rather than a service you can opt into yourself.

How many products support it

HMRC lists what each vendor declares. Feature flags, mobile-app support in particular, are vendor claims rather than verified facts, and listings change. Check with the vendor before you buy. Data: HMRC find-MTD-software service (tax.service.gov.uk), scraped 5 August 2026.

Twenty-eight out of 122 is a small minority, and it is worth being precise about what the directory can and cannot tell you beyond that.

HMRC grades this feature pass or fail. A product either supports HMRC Assist or it does not, and there is no third state. That is different from the 16 tax-return items, where vendors can and heavily do register an "in development" commitment: those items carry over a thousand such grades across the directory, which is how you can tell that Monzo and Lloyds have both told HMRC they intend to build all 16.

No equivalent signal exists for HMRC Assist. So the 94 products without it are not 94 refusals, and reading them that way would be reading a gap in HMRC's grading schema as a statement of intent. They are 94 products whose plans the directory is silent about. If the feature matters to you and your preferred product lacks it, the only way to find out is to ask the vendor directly.

Which products have it

Some patterns worth reading out of that list.

It skews towards agent-facing and specialist filing software. Twenty-three of the 28 also offer agent software, well above the directory average. That fits the feature's shape: an accountant filing dozens of returns benefits far more from an automated error check than a sole trader filing one.

Some of the strongest free products have it. My Tax Digital, Clear Books Free, TaxHeaven, TaxUpdates, Abridge and Self Assessment Direct all support Assist and all list a free version. Ten of the 28 list a free version, so this is not a premium-only feature.

The big brands are split. QuickBooks and Clear Books support it. Xero, Sage, FreeAgent and most of the free bank tools do not, as graded on this scrape. The one bank-adjacent exception is Coconut Free.

Bridging and spreadsheet tools are well represented. Absolute Excel Income Tax Filer, Aligned.tax, CHM ITSA Bridge, 1 1 MTD Bridge and 123 e-Filing all support it, which makes sense: if your records live in a spreadsheet with no validation of their own, an HMRC-side check is worth more.

Should it change what you buy?

Honestly, for most people, no. It should be a tiebreaker rather than a requirement, and here is the reasoning in both directions.

Reasons to weight it heavily:

• You have employment income alongside self-employment. This is where HMRC's held PAYE data is most likely to catch a genuine mismatch that you would not spot yourself.
• You file for other people, or your accountant does. The value scales with the number of returns.
• Your records live in a spreadsheet with no internal validation.
• You have been enquired into before, or you simply want the extra check.

Reasons not to:

• It cannot fix what it cannot see. HMRC holds PAYE data, not your receipts. Miscategorised expenses, missed income that nobody reported to HMRC, and honest arithmetic errors inside your own bookkeeping are all invisible to it.
• Five messages maximum, only when HMRC thinks something is wrong. Most people, most quarters, will see nothing at all.
• The features that decide whether software can file your return at all matter far more. If a product supports Assist but cannot handle your foreign property or your CIS deductions, Assist is irrelevant to you.

Put it below income-source coverage, below the 16 tax-return items, below price and below whether you will actually use the thing. Then, if two products are otherwise level, take the one with Assist.

Where TapTax sits, honestly

TapTax does not currently integrate HMRC Assist. It sits on the roadmap behind the work that matters more for filing completeness, and it needs production credentials with HMRC to build against properly. We would rather tell you that here than let you find the gap after signing up.

For completeness on status, since it bears on any comparison you are making: TapTax is MTD-compatible and going through HMRC's recognition process, and it does not appear on the find-software directory as of the 5 August 2026 scrape. Every product named on this page is listed today.

What TapTax does do on submission quality is different in kind: a running tax estimate as your transactions land, AI categorisation with a review flow for low-confidence items, and a fully verified fraud-prevention header implementation checked against HMRC's own validation service. Those reduce the chance of an error reaching HMRC in the first place, which is a different job from HMRC catching one afterwards. Both are useful. Neither replaces the other.

You can filter the directory for HMRC Assist yourself on the MTD software directory, and our analysis of all 122 tools covers the features that should outrank it in your decision.

The short answer

HMRC Assist is HMRC checking your homework against its own records and telling you, inside your software, when something does not add up. It is real, it is useful, and it is available on 28 of the 122 listed products. The directory will not tell you whether any of the other 94 is building it, so if the feature matters to you, ask the vendor.

Treat it as a bonus on a product you were going to choose anyway. If you have employment income alongside a trade, or you file for others, move it up your list. If your return is one trade and nothing else, the feature will probably stay silent for years, and the things that decide whether your software can file at all deserve your attention first.