Most TOMS VAT mistakes are not made by people who don’t care. They are made by people who assumed TOMS worked the same way as standard VAT, or whose accountant assumed the same. By the time anyone looks properly at the numbers, the problem has been compounding quietly for two years. Sometimes three.
These are the mistakes I see most often in UK travel businesses — and what each one actually costs.
Mistake 1: Applying standard VAT where TOMS should apply
This is the most common one, and also the most expensive.
A travel business buys in accommodation, transport or excursions from suppliers and resells them to customers in its own name. That is a principal transaction. TOMS applies. But the accountant — or the business owner handling their own bookkeeping — applies standard VAT instead. They charge VAT on the full selling price, reclaim input VAT on costs, and file the return.
It looks correct. The numbers add up. The return gets submitted.
What has actually happened is that VAT has been calculated on the wrong basis. The output VAT figure is overstated. Input VAT claims may be invalid under TOMS because costs absorbed into the margin cannot also be reclaimed separately. The VAT position for every period filed on this basis is wrong.
Correcting this requires going back through every affected period, recalculating margins from scratch and amending returns. HMRC charges interest on underpaid VAT. If the error is considered careless, penalties apply on top.
For ATOL licence holders specifically, this error has an additional consequence — read more about how incorrect VAT treatment affects ATOL accounting.
The business has usually been overpaying VAT for months or years without knowing it — which means it has also been understating profit. Both problems need correcting at the same time.
Mistake 2: Treating all income as commission when it is not
Some travel businesses operate as agent on some transactions and as principal on others. Commission income, where you are genuinely acting as agent and earning a fee for arranging a service on behalf of someone else, is treated differently from margin income under TOMS.
The mistake is to classify income as commission when the underlying transaction structure means the business is actually acting as principal. This is often done to avoid TOMS — either deliberately or because the distinction was never properly analysed.
HMRC’s view on this is not ambiguous. If you are contracting with the customer in your own name, carrying the risk if the supplier fails, and taking the margin between cost and selling price — you are a principal. Commission treatment does not apply. TOMS does.
Misclassifying principal income as commission produces incorrect VAT returns, distorted profit margins and a growing exposure that becomes harder to unwind the longer it continues.
The question of whether you are operating as principal or agent is not one to guess at. It requires a proper analysis of each transaction type in your business — what contract is in place, who carries the risk, how the income is structured.
Mistake 3: Getting the margin calculation wrong
Even businesses that know TOMS applies often calculate the margin incorrectly.
The margin under TOMS is the difference between what the customer pays for the travel service and the direct costs of the bought-in components. It sounds straightforward. In practice, it requires clean cost allocation — every bought-in cost must be correctly identified, correctly attributed to the relevant booking, and recorded in the right period.
The mistakes here are usually not dramatic. They are small and consistent: costs allocated to the wrong category, timing differences between when bookings are made and when costs are recorded, mixed supplies not properly separated. None of these trigger immediate red flags. They accumulate.
Over a VAT quarter, a small error in margin calculation changes the output VAT figure by a modest amount. Over two years of quarterly returns, that modest error becomes a meaningful one. And when it is eventually identified — whether internally or by HMRC — the correction requires reconstructing the margin calculation for every affected period.
This is why the bookkeeping structure matters as much as the VAT knowledge. Spreadsheets are not adequate for this. They cannot enforce consistent cost allocation, they do not flag timing mismatches, and they do not scale cleanly as booking volumes grow.
Mistake 4: Misunderstanding the VAT registration threshold
TOMS businesses often misunderstand when they need to register for VAT.
The VAT registration threshold in the UK is based on taxable turnover — not on the TOMS margin. This is widely misunderstood. A travel business that applies TOMS may have a relatively small margin, but a large gross turnover from customer receipts. The registration threshold is triggered by the gross turnover, not the margin on which VAT will eventually be calculated.
The consequence of this misunderstanding is delayed registration. A business that monitors margin rather than turnover may not realise it crossed the registration threshold months ago. When this is identified, HMRC requires backdated registration, backdated VAT accounting and payment of VAT that should have been collected from customers during the period of non-registration — which the business now has to fund itself.
This is one of the cleanest examples of a TOMS mistake that is entirely avoidable with correct advice from the start.
Mistake 5: Excluding EU travel services incorrectly
Under UK TOMS — post-Brexit — the VAT treatment of travel services enjoyed outside the UK changed. Travel services enjoyed wholly outside the UK are now outside the scope of UK VAT. This affects how the margin is split between in-scope and out-of-scope supplies.
The mistake is either to apply UK VAT to supplies that are now outside scope, or to incorrectly calculate the split between UK and non-UK services in a mixed itinerary.
Both versions of this mistake produce incorrect output VAT figures. The first results in VAT being charged where it should not be. The second distorts the in-scope margin and therefore the VAT due.
This area changed materially after Brexit and has not been widely communicated in plain terms to travel businesses. Many businesses are still applying pre-Brexit logic to post-Brexit transactions without realising the rules shifted.
Mistake 6: Discovering the error because HMRC found it first
None of the above mistakes are impossible to correct. The cost of correction is higher when HMRC identifies the error before the business does — because at that point, the business is no longer correcting voluntarily. It is responding to an enquiry.
Voluntary disclosure attracts lower penalties than errors identified under investigation. A business that identifies and corrects its own TOMS errors before HMRC involvement is in a significantly better position than one that receives a letter first.
This is why a review of historic TOMS treatment — not just compliance going forward — matters when a business is starting with a new accountant or when there is any uncertainty about whether previous returns were filed correctly.
If your TOMS treatment has never been properly reviewed, the question is not whether there are errors. The question is when they will surface and who will find them first.
These are the TOMS VAT mistakes I see most often in UK travel businesses — and what each one actually costs.
What correct TOMS VAT treatment looks like for travel businesses
It is not complicated once the structure is right.
The business structure is correctly analysed — principal vs agent is clear for each transaction type. The bookkeeping captures costs against the right bookings in the right periods. The margin calculation is consistent and reviewable. The VAT return reflects the correct in-scope margin. The registration threshold is monitored on the right basis.
None of this requires unusual effort once it is set up correctly. It requires specialist knowledge to set up, and consistent attention to maintain.
If you are a UK travel agent or tour operator and you are not certain whether your TOMS VAT treatment has been applied correctly, the time to find out is before your next return — not after HMRC asks the question.
If you have recently switched accountants or are thinking about switching, a review of historic TOMS treatment should be part of the conversation from the start.
What happens on a discovery call with LAS Accounting
I ask about your current setup, your VAT treatment, your bookkeeping structure, and whether TOMS has been applied correctly. I look at what you have. I tell you honestly what needs to change and whether I can help.
If it’s not a fit, I say so.
If you are a UK travel agent, tour operator or travel agency and you have been wondering whether your accounting is actually correct — not just filed, but correct — Talk to a specialist about your current setup.
