It happens every January, and most founders only notice when something goes wrong. By the 31st, every platform you sell on has filed its seller report with HMRC. Your numbers for the whole of the previous calendar year, broken into quarters, sitting in a government database before you have even opened your accounts.
At £1m and below, this is survivable. One channel, one settlement file, one spreadsheet, and the gaps are small enough to wave through. Past £1m it stops being survivable, because the gaps stop being small. Multiple channels, VAT on top of everything, refunds, fees, reserves, timing. Every one of those is a line that can quietly open up between what HMRC received and what you declared.
This post is about that gap. Not the rules in general, our platform reporting primer covers who reports and why. This is the £1m+ version: what HMRC actually receives, what it compares it against, and the bridge that stops messy books from looking like fraud.
What HMRC Actually Receives
The rules have been live since 1 January 2024, and they follow the OECD's model rules for digital platforms. HMRC's own guidance is blunt about what platforms send: your identity, the total amount paid to you for each quarter of the year after all deductions, any fees, commissions or taxes the platform withheld or charged, and the number of transactions you received payment for.
Read that list twice, because every word matters. It is not a description of what you sold. There is no item-level product data, no SKU list, no margin breakdown. It is the money side: what the platform paid you, what it kept, and how often you got paid.
Two details most people miss. The amounts are reported in whole pounds, not pennies, so the file is rounded before it ever reaches HMRC. And the whole thing lands by 31 January for the previous calendar year, so the 2025 data arrived in January 2026, and the 2026 data will arrive in January 2027.
There is a small-seller exemption, and you should know it precisely so you do not lean on it by accident. A platform does not have to report you if you made fewer than 30 sales of goods in the year and received no more than 2,000 euros, about £1,700, for those sales. Both conditions have to hold. If you do £1m+, you are nowhere near the exemption, and neither is anyone else on the platform who sells at scale.
One more thing worth knowing: the platforms give you a copy of what they filed. That copy is the single most useful document in your reconciliation, and most £1m+ founders have never looked at theirs. We will come back to it.
Why the £1m+ Version Breaks
Here is the uncomfortable truth about the easy version of this reconciliation. It works when your books and the platform file measure the same thing. At scale, they stop measuring the same thing, and the differences are not errors, they are structure.
First, VAT. Your returns are VAT-exclusive. Your turnover on your corporation tax return, and box 6 of your VAT return, are normally net of VAT. The platform reports what was paid or credited to you after its deductions, and for your own standard-rated UK sales that figure will usually include the VAT inside customer payments. On a channel doing £1.2m of customer takings, the VAT element alone is £200,000. If nobody explains it, that £200,000 looks like undeclared turnover. It is the single biggest line in the bridge, and the most commonly missing one. Whose VAT is whose, and when the marketplace collects it, is covered properly in our marketplace VAT guide.
Second, fees. The platform reports what it withheld separately from what it paid you. Add the two back together and you get back towards customer money. But the fees themselves carry VAT you reclaim, so there is a second VAT layer hiding inside the deduction lines. Amazon charges 20% VAT on most of its UK seller fees. TikTok's commission is 9% including VAT, so one sixth of it is reclaimable input tax. On a £2m brand selling mostly through TikTok and Amazon, those fee-VAT reclaims can easily run to five figures a year, and if your fee lines are booked to non-VAT codes, the reclaim never happens and the bridge line stays wrong.
Third, refunds and timing. The platform file is built on what was paid and settled. Your books are built on what was ordered and invoiced. A December sale refunded in January can land in your books as one year's number and in the platform's file as another's, depending on how each of you records it. A month of settlement lag can do the same. None of it is fraud. All of it looks like a mismatch until it is documented.
Fourth, the multi-channel problem. Each reporting platform operator files its own submission for each calendar year, so a brand selling through Amazon, TikTok and eBay usually ends up in three separate files, each with its own fee schedule, its own settlement rhythm and its own copy of the report. HMRC's system, Connect, cross-checks third party data against what you file. It does not need to understand your business to flag a gap. It just needs the gap.
The Bridge: A Worked Example
Let me show you what this looks like with real numbers. Take a brand doing £2.4m of customer takings a year across Amazon and TikTok Shop, all standard-rated goods, all its own UK sales. The customer money includes £400,000 of VAT, because one sixth of £2.4m is £400,000. So the pre-refund net sales figure is £2m, and that is what belongs on the corporation tax return and in box 6 of the VAT return, before refunds.
The platforms charged £300,000 of fees over the year, VAT included, and £50,000 of that is reclaimable fee VAT. Refunds issued came to £36,000, and they carried £6,000 of VAT with them, so they reverse £30,000 of net sales and £6,000 of output VAT. The cash that actually landed in the bank account was £2.4m of customer money, minus £36,000 of refunds, minus £300,000 of fees. That is £2,064,000, and it should tie to the bank with no residue.
Now the platform file. The platforms paid out £2,064,000 between them, and they withheld £300,000 in fees. So the file adds up to £2,364,000, which is your customer money minus the refunds. Compare that to your net revenue after refunds of £1,970,000 and there is a £394,000 gap. Panic territory, unless you can bridge it. You can, in three lines:
| Line | Amount | Where it lives |
|---|---|---|
| Platform file total (paid out plus fees withheld) | £2,364,000 | The copies the platforms sent you |
| VAT inside customer money, already accounted on your VAT returns | £394,000 | VAT return boxes 1 and 6 |
| Net revenue after refunds, per your books | £1,970,000 | Profit and loss, corporation tax return |
Check the arithmetic. The £394,000 is your £400,000 of output VAT less the £6,000 that came back with the refunds. £2,364,000 minus £394,000 is £1,970,000. That is your net sales of £2m minus the £30,000 of net refunds. It ties. And the £50,000 of fee VAT is the reason the fees line on your profit and loss is £250,000 while the platform withheld £300,000. Every number has a home, and the VAT return is where the missing £394,000 and the fee VAT live.
That is what a bridge looks like. It is boring, it is three lines, and it turns a £394,000 red flag into a document you can put in front of HMRC without sweating. We build these for every client we take on, and we have never met a £1m+ file that did not need one.
The D2C Blind Spot
Here is the part that surprises most founders, because it cuts both ways. HMRC's definition of a digital platform excludes software that only processes payments or only helps design and maintain a website. Shopify Payments does not make Shopify a reporting platform for your direct sales. Your own website, your wholesale accounts, your trade shows, none of that appears in any platform file.
So the picture HMRC holds is partial. It knows what Amazon and TikTok Shop and eBay filed about you. It does not know your Shopify channel from the platform data, and it does not know your direct accounts. That means two things.
One: if your marketplace numbers are reconciled but your D2C revenue is missing from your returns entirely, platform data will not catch it. Your bank account will, eventually. The data gap is not a hiding place, it is just a slower trap.
Two: your declared turnover will not equal the sum of the platform files, because it includes channels HMRC cannot see, and because the platform numbers carry their own VAT and timing differences. The bridge has to explain the whole difference, not just the D2C slice. When a compliance officer opens your file and sees turnover of £2.8m against platform data of £2.36m, the question is not whether you under-declared. It is whether you can show what the difference is made of. If you can, you are done. If you cannot, the questions get longer.
What Happens When It Does Not Match
Let me be straight about the consequences, because the stakes are what make this worth doing properly. HMRC's Connect system can cross-check the platform data against what you file. A material gap may trigger a nudge letter asking you to check your returns, or the opening of a compliance check. Either way, the clock starts, and the quality of your records decides how it ends.
For corporation tax, HMRC can normally go back four years, six if it decides the error was careless, and up to twenty if it decides the error was deliberate. Penalties can reach 100% of the lost tax for a deliberate and concealed inaccuracy, with interest on top of the tax itself. That is the extreme. If it goes badly, expect an assessment of extra tax, interest, and a penalty sized by how HMRC judges the error. A clean, documented bridge is the difference between "here is the VAT line, here is the refund timing, here is the whole-pound rounding" and "we are still reconstructing the file".
If you get a letter, do not panic, and do not reply from memory. Pull the copies of the platform reports, pull the settlement files, build the bridge, and respond with the document. If that sounds like a job for someone who does this daily, it is. That is literally what we do.
Your Calendar
This is not an annual scramble. It is three dates a year, and the work is mostly done before January ever arrives.
Monthly, when you close the books: reconcile each platform's settlement file to the bank, and keep the fee and VAT splits visible. That is the raw material. Our TikTok Shop reconciliation guide and our Amazon FBA deep dive walk the platform-specific mechanics.
Quarterly, when your VAT return goes in: the VAT lines in the bridge, the output tax on your own sales and the fee VAT reclaim, have to agree with what you filed. HMRC's platform data is quarterly too, which makes the VAT return the natural checkpoint.
By 31 January each year: download the copy of the report each platform filed, and run the bridge against your year-end figures before you file anything. Then the January handover is a confirmation, not a surprise. The January 2026 handover, which we covered in depth in our data handover warning, is exactly the shape of every one to come.
And if you are a sole trader or a landlord running your brand through personal accounts rather than a company, add one more layer: Making Tax Digital for Income Tax has been live since 6 April 2026 for sole traders and landlords with qualifying income over £50,000, with quarterly updates on top of the annual return. Partnerships are not in scope yet. The platform data and the quarterly updates will be sitting in the same system, so the bridge matters even more.
Frequently Asked Questions
At what point does HMRC know about my platform sales?
Since 1 January 2024, platforms have collected seller data and filed it annually by 31 January for the previous calendar year. So HMRC has had your 2024 numbers since January 2025 and your 2025 numbers since January 2026. If you sell at £1m+, there is no threshold hiding you: the small-seller exemption needs fewer than 30 goods sales and no more than €2,000 a year, and at £1m+ you fail the value test comfortably.
Does the platform report include VAT?
The platform reports what it paid or credited to you after its deductions. For your own standard-rated UK sales, that figure includes the VAT inside customer payments. Your returns are VAT-exclusive. That difference is the biggest line in the reconciliation bridge, and it is why your declared turnover will never simply equal the platform file. The VAT sits on your VAT return, and the bridge shows where.
My books do not match the platform report. Am I in trouble?
Not automatically. Refunds, settlement timing, VAT treatment, whole-pound rounding and fee splits all create legitimate differences. What matters is whether you can document them. Build the bridge line by line, keep the copies of the reports, and the difference stops being a problem. What gets people into trouble is an unexplained gap and no paperwork.
Does HMRC see my Shopify sales?
Not through platform reporting. Software that only processes payments or only helps design and maintain a website is not a digital platform for these rules, so Shopify Payments alone does not trigger a report. Your direct sales still go on your returns, and your bank records can be checked, so the gap in HMRC's file is not a gap in your obligations.
Is the report a tax bill?
No. The report is information sharing, not a tax assessment. It does not automatically mean tax is due. HMRC uses it to check what you declare, and it is shared with other countries' tax authorities where the same rules apply. At £1m+, the trading is not in question. The question is whether the numbers match.
Do I need to match the platform file to the penny?
No, and do not try. The file is in whole pounds, it is calendar year while your tax year runs to 5 April, and it is built on settlement rather than invoicing. A documented bridge that explains every material line is what survives a compliance check. Chasing pennies is what founders do when they are avoiding the real reconciliation.
Summary: Build the Bridge Before You Need It
HMRC has had platform data on UK sellers since January 2025, and the 2025 data landed in January 2026. The system is not coming, it is here, and it is quarterly, rounded and merciless about gaps.
The fix is not complicated. Know what the platforms file: quarterly amounts after deductions, fees and taxes withheld, transaction counts. Know what your returns show: VAT-exclusive turnover. And keep a bridge that explains every line between the two, including the VAT, the refunds, the timing and the channels HMRC cannot see.
Turnover is vanity, profit is sanity, cash is reality. And the platform file is the one number you do not get to define. Someone else already filed it.
If you are doing £1m to £20m across Amazon, TikTok Shop or your own site, and you have never seen the copy of the report your platforms filed, that is exactly the conversation we should have. Book a call and we will look at your real files and build the bridge before HMRC asks for it. See how we help Amazon sellers and TikTok Shop sellers.