August is the quiet month in the platform reporting calendar. No one is filing anything. Your VAT return went in weeks ago, your accountant is on holiday, and the whole thing feels like next year's problem.
It is not. Right now, HMRC holds two years of platform reports about your marketplace sales. The 2024 numbers were due by 31 January 2025. The 2025 numbers were due by 31 January 2026. And the 2026 report, broken into its four quarters, is being assembled as you read this, because every platform you sell on has been collecting the data since January.
I spend my days looking at those files. Not the rules in the abstract, the actual seller reports platforms file with HMRC, and the copies they send back to sellers. Two years in, the pattern is clear. The grace period is over. HMRC has enough history now to compare what it received against what you declared, and the gaps it finds are the ones nobody documented.
So here is the 2026 action list. Eight things, in order, with the deadlines that matter. Do them now, in the quiet month, and January stops being a scramble.
The Quick Summary
Five minutes today: find out which platforms file about you, and download the copies of last year's reports. One morning this month: reconcile those reports to your books and write down the differences. That is 90% of the work. The rest of this list is about not undoing it.
Action 1: Know Which Platforms File About You
The digital platform reporting rules went live on 1 January 2024, and they follow the OECD's model rules. Marketplace-type platforms report sellers. In practice, for a scaling UK brand, that means Amazon, TikTok Shop, eBay, and any other marketplace where you register as a seller.
What do they report? Your identity and tax identifiers, the total paid or credited to you for each quarter of the calendar year after all deductions, the fees, commissions or taxes the platform withheld, and the number of transactions you received payment for. That is the whole file. There is no item-level product data, no SKU list, no margin breakdown. It is the money side, and for UK sellers it is reported in whole pounds, not pennies.
Here is the part that surprises people. Software that only runs a website or only processes payments is not a digital platform for these rules. So Shopify Payments does not make Shopify a reporting platform for your direct sales. Your own website, your wholesale accounts, your trade show orders, none of that appears in any platform file. The picture is partial in a specific direction: it sees your marketplace money, it does not see your direct money.
Write the list down anyway. Amazon, TikTok Shop, eBay, anywhere else you sell. For each one, ask the same question: does this platform file about me? If it is a marketplace where you are a registered seller, the answer is usually yes. Our platform reporting primer walks through who reports and why, and yesterday's post on reconciling platform reporting at £1m+ covers what HMRC actually receives in detail.
Action 2: Get Your Copies of the Reports
Here is a rule most founders have never heard, and it is the most useful one in this post. Platform operators have to give you a copy of the information they reported to HMRC. Not may. Have to.
So where is yours? For each platform on your list, go looking. Seller dashboards keep these under tax documents, statements or reports. If you cannot find it, message seller support and ask for the copy of the report you are entitled to. It exists, it is in your name, and the platform is obliged to give it to you.
What you will see: the total you earned on that platform for the calendar year, less any fees, commission or taxes the platform deducted, broken into the four quarters of the year. It may come as a PDF, a spreadsheet or a dashboard download. Whatever the format, it is the single most useful document in your entire year-end, and at £1m+ most founders have never opened theirs.
Do not confuse the report with a tax bill. It is not one, and it does not automatically mean tax is due. What it is, is the exact shape of what HMRC now knows about you. Treat it like a mirror, not a letter.
Action 3: Check the Small-Seller Exemption Is Not Your Excuse
The rules do have an exemption, and you should know it precisely, because leaning on it by mistake is how people get into trouble. A platform does not have to report you if you made fewer than 30 sales of goods in the calendar year and received no more than 2,000 euros, about £1,700, for those sales.
Both conditions have to hold. Fewer than 30 sales. €2,000 or less. If you are reading this because your brand is scaling, you cleared the value test in a weekend. You are nowhere near the exemption, and neither is anyone else on the platform doing serious volume. Drop this one and move on.
Action 4: Reconcile Every Report to Your Books Now, Not in January
This is the real work, and it is why you are reading a post about it. The platform file and your books do not measure the same thing, and the differences are not errors, they are structure.
Take the biggest line first: VAT. Your returns are VAT-exclusive. The platform reports what was paid or credited to you after its deductions, and for your own standard-rated UK sales that figure includes the VAT inside customer payments. On a channel doing £1.2m of customer takings, the VAT element is £200,000. If nobody explains it, that £200,000 looks like undeclared turnover to anyone comparing files, including a computer.
Then fees. The platform reports what it withheld separately from what it paid you. Platform fees often carry VAT you can reclaim, so a second VAT layer hides inside the deduction lines. Not every fee line qualifies, which is why the split has to stay visible. Then refunds and timing. The platform file counts money when it is paid or credited to you, after refunds and cancellations in that period. Your books count a sale when it happens, under your accounting basis. A December sale refunded in January can sit in two different years depending on who is counting.
None of it is fraud. All of it looks like a mismatch until it is written down. The fix is a bridge: a short document that shows, line by line, how the platform file total becomes the revenue on your profit and loss. Our deep dive on the bridge has the full worked example, and the platform-specific mechanics live in the TikTok Shop payout guide and the Amazon FBA deep dive. If you sell across all three, the multi-marketplace finance stack post shows how the files fit together.
Do it per platform, once a quarter, when the VAT return goes in. The platform data is quarterly too, which makes the VAT return the natural checkpoint. Quarter one of 2026 is already behind you. Quarter two too. If you have not checked either against your books, that is your first job this week.
Action 5: Make the Calendar-Year Translation Explicit
The platform file runs January to December. Your corporation tax return runs on your accounting period, and a personal return runs 6 April to 5 April. Same money, three different frames.
This is not a paperwork nit. When HMRC's systems cross-check third-party data against what you file, they compare the platform's calendar-year numbers with your declared figures. If your year end is not 31 December, the two can never line up by construction, and the difference has to be explainable on paper, not in your head.
Write down, once, how your accounting period maps onto the calendar year the platform reports. Keep that note with the bridge. It sounds trivial. It is the difference between a two-minute answer and a two-hour reconstruction.
Action 6: Sort the Personal Layer, If It Applies
So far this is all company stuff. But the rules do not care about your corporate structure. If you, personally, sell through any platform, you are in scope too.
For individuals the bar is low and the rules are generous at the bottom. You get a £1,000 trading allowance each tax year. Gross trading income of £1,000 or less, you generally do not need to tell HMRC, though you should still keep records. Sell personal possessions from your house, a loft clear-out or a wardrobe cull, and it is usually not trading at all. It only becomes a tax question if a single item or set goes for more than £6,000, the capital gains threshold. The line is drawn where the intent appears: if you buy or make goods intending to sell them for a profit, you are probably trading, and the allowance is the cushion you get.
And here is the 2026 bit. Making Tax Digital for Income Tax went live on 6 April 2026 for sole traders and landlords with qualifying income over £50,000. That means quarterly updates to HMRC, on top of the annual return, through software. The threshold drops to £30,000 in April 2027 and £20,000 in April 2028. Partnerships are not yet in scope, and there are no penalty points in 2026-27. HMRC's sign-up drive starts in September, and more than 436,000 first quarterly updates have already been filed. HMRC receives both datasets, and it has said platform data will be used to check whether taxable income was properly declared. Assume they will be compared.
If you run your brand through a company and sell personally on the side, work out whether the side hustle crosses the £1,000 line and get it on a return if it does. The platform data will find it eventually, and getting in front of it costs nothing.
Action 7: Keep the Records That Answer Questions
When a compliance officer opens your file, they are not looking for fraud. They are looking for a gap they cannot explain. Your job is to make every gap explainable, and that is a records job.
Keep the copies of the platform reports, every one, every year. Keep the settlement files behind them. Keep the bridge. Keep the fee and VAT splits visible, because the reclaims live in there. VAT records stay for six years. Corporation tax records stay for six years from the end of the accounting period. Self-employed records stay for five years after the January filing deadline. The platform reports belong in that pile, and the pile is not optional.
If you are not sure your bookkeeping preserves this, the 12-step monthly accounting checklist is the closest thing to a maintenance manual.
Action 8: Know What a Letter Looks Like Before It Arrives
HMRC does not need to write to you to use the data. But when it does write, the letters that matter come in two flavours, and they are different.
First, Simple Assessment. If HMRC can work out your tax from information it already holds, and you are not required to file a Self Assessment return, it can calculate the bill itself and send it to you. The bill is legally due, late payment interest builds once it passes the due date, and HMRC has publicly urged people not to ignore the letters. You normally have 60 days from the date on the bill to challenge or query it, and the clock runs from that date, not from when you open it.
Second, the nudge letter or compliance check. A material gap between platform data and your returns can prompt HMRC to take a closer look, from a nudge letter asking you to check your returns to the opening of a compliance check. If one arrives, do not panic, and do not reply from memory. Pull the report copies, pull the settlement files, build the bridge, and answer with the document. For corporation tax HMRC can normally go back four years, six if it decides the error was careless, up to twenty if it decides it was deliberate. Penalties can reach 100% of the lost tax for a deliberate and concealed inaccuracy. The extreme cases make the headlines. The ones that actually happen are letters that say please check your returns, and they are answered with paperwork, not panic.
One more thing worth saying, because it is the scariest sentence in this post and it is true. HMRC does not need to understand your business to flag a gap. Its systems just need the gap.
Your 2026 Calendar
Here is the whole year on one page.
| When | What to do |
|---|---|
| This month | Map your platforms. Download every report copy you are entitled to. Check the small-seller exemption does not apply to you. |
| Monthly | Reconcile each platform's settlement file to the bank. Keep fee and VAT splits visible. |
| Quarterly | Check the platform's quarterly figure against the VAT return. Update the bridge. |
| September 2026 | If your qualifying income was over £50,000 and you are not signed up yet, act now. HMRC's sign-up drive starts this month, and the first quarterly update was already due on 7 August. |
| By 31 January 2027 | Platforms file their 2026 reports. Download the new copies and run the final bridge against your year-end. |
| Before you file anything | The bridge is a confirmation, not a surprise. If it does not tie, find out why before you file, not after. |
The 31 January 2027 filing is the moment the 2026 data becomes official. Between now and then you have just over five months of quiet runway. Use it.
Frequently Asked Questions
Do I have to do any of this if my accountant handles the books?
Yes, one bit of it. The report copies come to you, not to your accountant. The platforms file in your name and send the copy to you. If you do not download them and hand them over, your accountant is bridging against a file they have never seen. Send the copies with the year-end pack, every year.
I never received a copy of my platform report. What now?
Ask the platform. The rules require platform operators to give sellers a copy of what they reported. If it is not in your seller dashboard, seller support can point you to it. If they cannot, keep a record of asking, and tell your accountant.
Is the platform report my turnover?
No. It is what the platform paid or credited to you, after its deductions, for the calendar year. It excludes your direct sales entirely, and for your own standard-rated UK sales it normally includes the VAT inside customer payments. Your turnover is a different number, and the bridge explains the difference.
I sell personal stuff on a marketplace as well. Does that get reported?
Possibly, and it usually does not matter. Selling personal possessions is generally not trading, so there is no tax to pay, and the £6,000 capital gains threshold for a single item covers most wardrobe clear-outs. The problem appears when buying to resell becomes a habit. Then you are probably trading, the £1,000 trading allowance or your actual expenses is the shield, and the platform data knows exactly what you took.
What happens if HMRC writes to me about a gap?
You answer with documents. The report copy, the settlement files, the bridge, the VAT return lines. If the gap has a home, the letter usually closes. If it does not, the questions get longer. That is the whole game.
Is there any good news in 2026?
Yes. The data is predictable. The rules have applied since January 2024, the reports follow the same shape every year, and the platforms are required to hand you a copy of what they filed about you. There is no guessing, only the work of checking, and it is a morning per channel per quarter, not a mystery.
The Bottom Line
Two years of platform reports are already in HMRC's hands. The 2026 report is being assembled right now, and by 31 January 2027 it will be filed. You cannot stop that. You can decide, today, in the quiet month, whether your books are ready to meet it.
Download the reports. Build the bridge. Keep the records. That is the whole action list, and it turns the scariest sentence in this post into a solved problem. The systems do not need to understand your business to flag a gap. A gap with a document behind it stops being a gap.
If you want this done properly, before the letters arrive, book a call and we will look at your actual platform files and build the bridge with you. See how we help Amazon sellers and TikTok Shop sellers.