VAT Margin Scheme Software: Why Xero and QuickBooks Still Don't Do It (And Why We Didn't Build It Either)

The oddly specific problem

No mainstream accounting platform calculates VAT margin scheme VAT, and the one company that does already owns the search results.

Search for VAT margin scheme software and you will find a cottage industry of workarounds rather than products. Somewhere in the UK there is a bookkeeper who has, for about a year now, been maintaining a QuickBooks product-bundle hack so that a second-hand goods dealer's VAT comes out right. Not because bundles were designed for this. Because nothing else was.

The VAT margin scheme is straightforward arithmetic. You buy a used item, you sell it, you pay VAT on the difference at one-sixth. What is not straightforward is everything around it. HMRC wants a stockbook: stock number, purchase and sale dates, invoice numbers, both prices, buyer and seller names, item description, the margin, the VAT due. Kept for six years. And the sales invoice must not show VAT separately, which is precisely the one thing accounting software is built to do automatically.

So the workaround has calcified into a ritual. Calculate the margin in Excel. Raise an invoice with the VAT suppressed or manually overridden. Post a journal to book the VAT. Keep the stockbook in a separate file that the ledger knows nothing about. A bookkeeper described exactly this on the ICB forum back in 2016. Another described it on a QuickBooks forum in 2019. The Reddit thread that prompted this research is from 2025 and says the same thing, with more exasperation: how has no software company filled this hole?

Good question. It has an answer, and the answer is why we're not building it.

Wait, is this actually a problem?

Yes, and the pain has teeth. Get the margin scheme wrong and HMRC can refuse the scheme entirely, assess VAT on the full sale price rather than the margin, backdate it, add interest from the original due date, and apply a penalty of anywhere from nothing to 100% of the VAT depending on how careless or deliberate the error looks. That's a compliance failure with real numbers attached.

There's a second, subtler risk. Making Tax Digital requires an unbroken digital link from source records to submitted return. A spreadsheet stockbook can satisfy that, right up until a backdated purchase invoice turns up or someone recategorises a transaction after filing. Then the spreadsheet is stale and the link is theoretical. Nobody finds out until HMRC asks.

Money signals exist. Somebody sells an Excel template specifically for second-hand goods dealer margin scheme bookkeeping for £24.99 to £29.99 (as of research), and people buy it. Xero's product ideas forum has a request to automatically calculate margin scheme VAT sitting at 81 votes, with users posting workarounds across 2023, 2024 and 2025. In November 2025 Xero's community manager confirmed it isn't on the roadmap.

81 votes over several years, then the product team declined.

Read that vote count carefully, though. Eighty-one votes accumulated over several years, from a platform with a very large UK base, and the product team declined. That is as consistent with "too niche to build" as it is with "screaming unmet demand." We'll come back to it.

VAT margin scheme software: who's already solving this

The gap in this table is not "nobody solves it." The gap is that the only native solution asks you to leave your accounting platform.

So why isn't this a slam dunk?

We looked closely, and then stepped back. Three reasons, in order of how much they mattered.

The incumbent is the exact product. Our own research framed OneSixth as a "price anchor," which is a polite way of avoiding the fact that it is a direct competitor shipping the specification we'd have written: native stockbook, one-sixth calculation, MTD digital link, practice pricing. The plan implied by all this evidence was, essentially, "build that but £10 cheaper." Undercutting a founder-led product on a feature set defined by margin / 6 is not a strategy. They match the price inside a week, and now there are two subscale vendors in a small market instead of one.

The technical triviality is a liability. The core logic is a subtraction and a division. The MTD API is documented and has a sandbox. A competent solo builder ships a working version in six to eight weeks. That means no engineering moat exists for anyone, including the incumbent. The durable advantage here is distribution: accountant relationships, professional body credibility, and search visibility for "VAT margin scheme software." OneSixth has a head start on all three.

Undercutting a founder-led product on a feature set defined by margin / 6 is not a strategy.

At an optimistic £200 cost per organisation acquired, twenty orgs costs £4,000 against roughly £500 monthly recurring revenue. At realistic B2B professional-services acquisition costs, payback stretches past two years. Infrastructure runs about $54 a month, which is delightful and completely beside the point.

Two smaller things worth flagging, because they get overstated in this kind of analysis. The willingness-to-pay evidence is a one-time £25 spreadsheet purchase, which is a twelvefold annual difference from a £25 monthly subscription and a different buying decision entirely. And the lock-in argument is weaker than it looks: HMRC requires dealers to be able to produce six years of records, so any decent tool lets you export the whole stockbook, which means cancelling costs a customer almost nothing.

The market-size question also deserves honesty. Circulating estimates of "250,000 VAT-registered businesses in adjacent sectors" are unsourced and stretch the definition of adjacent past breaking. HMRC doesn't publish a count of active margin scheme users. Judging by the observable footprint (one busy forum thread, 81 votes over years, a cottage-industry spreadsheet), the real population is plausibly in the low thousands to low tens of thousands. That comfortably supports one focused business. Two is a coin flip.

That comfortably supports one focused business. Two is a coin flip.

What we're watching

The one angle that would change our answer: a plugin inside Xero or QuickBooks rather than a tool beside them. OneSixth competes against the accountant's existing platform; a marketplace app would compete within it, which removes the "another login, another system" objection that makes practices hesitate. It also swaps cold outreach for marketplace discovery, which is the closest thing to a low-cost channel this niche has. The trade-off is real: app store approval, platform API dependency, and the risk that Xero eventually builds it natively after all.

Specific triggers we'd act on:

• Xero or QuickBooks reversing course. If either adds native VAT margin scheme support, the standalone category loses most of its reason to exist. Watch that Xero product ideas thread for a status change.
• Signs OneSixth is stalling. Weak accountant integrations, poor support reputation, no visible growth. An underperforming incumbent in a small niche is an opening. A growing one is a closed door.
• Actual HMRC data on margin scheme registrations. If the real user population turns out to be much larger than the visible footprint suggests, the two-player maths changes.
• A named distribution channel nobody has claimed. An ICB or AAT partnership, a trade association for antiques and used-vehicle dealers, an accountant network with margin scheme clients concentrated in it.

Until one of those moves, the useful output of this research isn't a product. It's the table above, and the observation that if you have this problem today, someone already fixed it for £29 a month.