The Algorithm Already Has Your Number.

Everyone pictures a man in Newcastle spotting your account, slamming down his tea and dispatching a van. What actually exists is a database, a queue, and a legal calendar.

Right. Details.

Connect launched in 2010, built with BAE Systems Applied Intelligence. It cross references your return against dozens of outside sources: banks, Land Registry, DVLA, council tax, overseas tax authorities, digital platforms.

Mismatches score. In 2024/25 alone, Connect leads brought in an extra £4.6 billion.

Here is the bit nobody says out loud: being flagged is not being investigated. Plenty of mildly odd returns get looked at, shrugged at and left alone. HMRC has finite officers and a yield target.

Once your return is in, section 9A of the Taxes Management Act 1970 gives HMRC 12 months from the date you filed to open an enquiry. Hard deadline, not a vibe.

File late and it shifts to the quarter day following the first anniversary of when you actually filed. Quarter days are 31 January, 30 April, 31 July, 31 October. Filing late genuinely hands them extra time, which is one of many reasons not to.

Two things follow:

An enquiry notice is not an accusation. Plenty close with no changes whatsoever. (Decent plain English explainer here.)

Those durations are practitioner experience rather than published HMRC statistics, so treat them as shape, not promise.

The biggest variable you control is response speed. Enquiries rarely drag because HMRC is slow. They drag because documents arrive in dribs and drabs.

Not an enquiry. Not an accusation. Not statutory anything. Just a letter saying “we hold information, you may wish to review your position”, usually with 30 days on it.

They are designed with behavioural science input, which is my favourite detail in all of this. Deadline, social proof, implied consequence, and the strong impression they already know. Cheap to send in bulk. HMRC cannot formally investigate everyone, so it outsources the checking to you.

“Post a designer bag and HMRC will investigate you.” No.

One holiday triggers nothing. Holidays go on credit cards and get paid off slowly, which HMRC understands perfectly well, because HMRC employs humans who also have credit cards.

What generates a signal is convergence. Property on Land Registry, financed car on DVLA, frequent travel, declared income that could not plausibly service any of it, plus an actual data mismatch on the return. That combination is a pattern. A weekend in Mykonos is not.

Penalties for inaccuracies live in Schedule 24 of the Finance Act 2007, charged as a percentage of the extra tax that falls due once the error is corrected.

Domestic matters (offshore is harsher, another week):

Read the careless row twice. Getting there first is worth the entire penalty. Not a discount. The lot.

It does not mean “before the letter arrives”. Paragraph 9(2) says unprompted means you had no reason to believe HMRC had discovered, or were about to discover, the inaccuracy.

It is an objective test. Not what you felt. What the facts gave you reason to believe. Your sincere optimism is not a defence.

And “about to discover” is doing heavy lifting now that platforms file annual reports naming you.

Per HMRC’s own guidance, a general national campaign does not make your disclosure prompted. Being contacted to say your return is being checked does. Nudge letters sit in the middle and practitioners genuinely disagree. If one lands, treat your window as closing rather than closed. Advice that week, not that quarter.

Unprompted decides which band. Quality decides where in it you land: tell HMRC, help them quantify what is owed, give them access to the records. Timing counts too, so sitting on a known problem for two years still costs you.

Shoebox and a shrug is technically a disclosure. A poor quality one, priced accordingly.

Arguably bigger than the percentage:

The same £3,000 a year is a four year problem, a six year problem or a twenty year problem depending entirely on which word ends up on the file.

Two limits. Suspension is careless only; deliberate can never be suspended. And HMRC can refuse where it cannot identify a meaningful condition to set, which the Upper Tribunal confirmed this year. You can appeal a refusal to suspend. You cannot appeal their verdict at the end of the period, so treat the conditions as real.

HMRC is not a shark. It is a filing cabinet with a spreadsheet, a queue and a statutory calendar.

You get scored quietly. There may be a long silence. There may be a nudge before there is ever an enquiry. If an enquiry comes, it is months of letters, not a van.

At every point before that letter, your options are materially better than they will be afterwards.

HMRC has no category for adult creator. You are self employed, you earned money creatively, and you are reporting it. That is the entire story.

Questions about your own situation? Message me at @hmrcafterdark and let’s talk it through.

Keeping your own records for the first time? Start with The Adult Creator’s UK Tax Survival Guide 2026/27, your beginner info pack. It’s in your welcome email, and it’s free at hmrcafterdark.kit.com.