What a receipt proves, and what it cannot

Every small business in Finland has a version of the same drawer: a wad of thermal slips, some of them curling, a few already grey, kept because somebody said to keep them. Most owners could not tell you what the law actually asks of that drawer, and the ones who could are usually wrong about the interesting half.

So here is what a receipt is for, what has to be on it, and — the part almost nobody is told — the one thing it cannot do no matter how carefully you keep it.

The law's word for it is voucher

In the Accounting Act a receipt is a tosite, a voucher: the document that ties an entry in the books to something that actually happened. The Act says three things about it that are worth reading in the original order, because they build.²

What has to be on it

The VAT Act sets out a full invoice in section 209e: date of issue, a unique sequential number, the names and addresses of both parties, both VAT identification numbers where they apply, the quantity and nature of what was supplied, the date of supply, the taxable amount per rate, the unit price without VAT, any discount, the rate, and the VAT payable.¹

Nobody's lunch receipt carries all of that, and it does not have to. Finland allows a simplified invoice in four situations, and a café slip is one of them.

But simplified is not the same as unstructured. A simplified invoice must still carry the date of issue, the seller's name and VAT identification number, the nature and quantity of what was sold, and the VAT payable per rate — or the taxable amount per rate. Prices may be shown VAT-inclusive as long as the VAT amount is stated.¹

Read that list against the drawer and one defect turns up more than every other combined: a slip with no seller VAT number on it. It happens most often with small sellers, market stalls, and terminals somebody configured once. And it matters, because Verohallinto puts the condition plainly: a precondition for the right to deduct is that the purchaser holds an invoice, issued by the seller, that meets the requirements — and that the invoice “must correspond to the actual circumstances”.¹

The card slip is not the receipt

Two pieces of paper come out of a counter and they look like siblings. They are not.

The terminal slip proves that a card was charged a certain amount at a certain merchant at a certain minute. It says nothing about what was bought, which is the first thing on every list above, and it usually carries no VAT breakdown and no seller VAT number. As a voucher it fails on three counts at once.

It is still worth keeping — it is the cleanest link between a line on a bank statement and a purchase — but it is evidence of payment, not evidence of a purchase, and filing it instead of the receipt is one of the quietest ways to lose a deduction.

What no receipt can prove

Now the part that is rarely said out loud. Suppose the receipt is perfect: seller's VAT number, itemised, VAT per rate, legible, filed the same day. It still does not tell anybody whether you may deduct it.

Because deductibility does not turn on what was bought. It turns on why, and why is never printed on the paper.

Take one restaurant receipt: two people, a table, 84 EUR, VAT at 13,5 %. If the second person was a colleague and the meeting was internal, that is an ordinary business cost. If the second person was a prospective customer and the lunch was there to cultivate the relationship, it is entertainment — and the treatment changes twice over. Verohallinto lists “goods or services were purchased for an entertainment purpose” among the situations where input VAT cannot be deducted at all.³ And in income taxation only half of the expense is deductible; MyTax works the portion out for you once you have told it which pile the expense belongs in.⁴

Same restaurant. Same total. Same VAT rate printed on the same slip. Two different answers, and nothing on the paper distinguishes them.

A receipt is an excellent witness to what was bought. On why it was bought it has nothing to say — and why is the half that decides.

The law already knows this

This is not a gap somebody forgot to close. The rules are written as though everyone understands that the document and the justification are two different things.

Where a purchase serves business and private purposes at once, the right to deduct is limited to the part actually used for VAT purposes — and the taxpayer is “under a duty to substantiate this”. Verohallinto's own example is a driver's logbook: kilometres recorded, so there is proof of which distances were driven for which purpose.³

Look at what that example concedes. The fuel receipt is not in dispute. It is a perfectly good voucher. The thing being asked for is a second document that says what the first one was for. The logbook is the substantiation; the receipt is only the amount.

Which means a complete record of a business expense was never one piece of paper. It is a receipt, plus a sentence.

The sentence is the cheapest compliance you will ever buy

The sentence does not have to be good. It has to exist, and it has to exist now. Who, what for, and — if the expense is the kind that could be entertainment — who else was at the table.

Written at the counter it takes three seconds. Reconstructed in March from a bank statement it takes an hour, and what you produce at the end of that hour is worth less: it is a recollection about a Tuesday eleven months ago, and an inspector can see from the timestamp that it was written last week. Contemporaneous notes are believed. Reconstructions are negotiated.

• Does the slip carry the seller's VAT number?The single most common defect, and the one that takes the deduction with it.
• Does it say what was bought, not just what was paid?If it says only an amount and a merchant, you are holding the card slip.
• Is the VAT shown per rate?A single total with mixed rates inside it cannot be split afterwards without guessing.
• Is the purpose written down, and written today?One line. It is the document the receipt cannot be.
• If anybody outside the company was present, is that on the note?It is the fact that decides entertainment, and it is the fact nobody remembers in March.
• Is there a copy that will still be readable in 2032?Section 7 asks for readable and printable, for six years. Thermal paper does not promise that.

Paper that erases itself

Thermal receipts are printed by heating a coating rather than by putting ink on a page, and the coating goes on reacting to heat, light and time long after it leaves the shop. A slip that spends a summer in a car, or eighteen months in a wallet against a warm pocket, comes out grey. Nobody decided this; it is what the paper is.

Set that against section 7: reviewable without difficulty, printable in clear written format, for the whole retention period. A receipt you cannot read is not a receipt, and the six-year obligation did not fade along with it.

The Act is not attached to paper, though, and never was. Sections 7 and 9 are about contents — reviewable, printable, producible in Finland without undue delay — and say nothing about what the contents are written on. Keeping the drawer electronically is not a workaround anybody tolerates; it is the straightforward reading of what is asked for. Photograph it the day it is issued, while it is still black.

When the receipt is gone

The honest answer is short and not the one people want. The condition Verohallinto states is that you hold an invoice meeting the requirements.¹ No document, no VAT deduction. A line on a card statement is not a substitute, for exactly the reason above: it records a payment, not a purchase.

The practical move is unglamorous and works more often than people expect: ask the seller for a copy. They are keeping their own copy for six years under the same Act, and most of them can reprint it from the same till that issued it. That is a two-minute email, and it is available for roughly the length of time anybody would care.

This is where small businesses lose money quietly. Not in a dispute — in a drawer, one faded slip at a time, and it never appears as a line item anywhere.

What this means for software

A machine can read a receipt well now. It can find the seller, the VAT number, the rates, the totals, and tell you the slip is incomplete before you file it — all of that is on the paper, and reading paper is the part that got cheap.

The field that decides the treatment is not on the paper. Which means there are only two possible designs: ask for it, or invent it.

We ask. An engine that cannot derive a field asks for it by name, and purpose is the clearest example of a field nothing can derive — because the answer was in the room and not in the document. A system that fills it in with the most probable value is filling in the half that decides the deduction, with a guess, in a field nobody will ever check precisely because it was already filled in.

Everything else in this article is the software's job. That one line is yours, and it takes three seconds at the table.