An invoice that misses a mandatory element will not hold up in a tax audit – whether you claim it as a cost or as input VAT. In both Slovakia and Czechia the rules are largely aligned with the EU VAT Directive, yet the paragraph references, thresholds and even the currency on simplified invoices differ. This is where a document that merely looks like an invoice parts ways with one that actually stands up to scrutiny.
Why do auditors care about the content, not just the existence of a document?
During a tax audit it is not enough that you hold a document. The inspector examines whether the cost or the VAT deduction is properly evidenced – whether the document clearly states who supplied what, to whom, when and for how much. If a required detail is missing or wrong, the tax authority may remove the cost from the tax base or reject the input VAT. The company then pays more tax even though the transaction genuinely took place.
Sound record-keeping is therefore protection against additional assessments and penalties, not paperwork for its own sake. If you run a company across both markets, it helps to understand how the two systems compare – we set out the wider picture in our overview of Slovak tax advisory for companies.
What is the difference between an accounting document and an invoice?
The accounting document is the broader concept: it covers every provable record of a transaction – cash receipts, bank statements, internal vouchers and invoices alike. An invoice is simply one type of accounting document used for the sale and purchase of goods or services. Every invoice must therefore meet the requirements for an accounting document; when it is issued by a VAT payer, additional details required by the VAT act apply on top.
In practice a non-VAT payer issues an invoice that only needs to satisfy the accounting act, while a VAT payer must also watch the tax-document requirements. Confusing these two layers is a common source of errors that surface precisely during an audit.
What must an accounting document contain?
The accounting-document requirements are near-identical in both countries – in Slovakia under Section 10 of Act No. 431/2002 Coll., in Czechia under Section 11 of Act No. 563/1991 Coll. A document is provable only if it contains:
- a descriptive and numerical designation of the document,
- the content of the transaction and the parties involved,
- the monetary amount, or the unit price and the quantity,
- the date the document was drawn up,
- the date the transaction took place, if different,
- the signature record of the persons responsible for the transaction and for posting it.
These details apply even to an internal voucher used, for example, to post depreciation. A missing signature record or a vague description of the transaction is often what undermines the evidential strength of the document.
What extra details does a VAT invoice require?
A VAT invoice must additionally show the name and address of both the supplier and the customer together with their VAT identification numbers, a sequential invoice number, the date of supply (if it differs from the issue date), the issue date, the scope and nature of the supply, the taxable amount and unit price net of tax including any discounts, the applied tax rate and the amount of tax. In Slovakia these follow Section 74 of Act No. 222/2004 Coll.; in Czechia Section 29 of Act No. 235/2004 Coll.
The substance is harmonised across the EU, so the practical traps are the same: a missing customer VAT number, a wrong supply date, or a generic description such as “consulting” instead of the concrete service supplied.
When is a simplified invoice enough, and where do the two countries differ?
Both countries allow a simplified invoice that omits the customer’s identification details and the unit price. The key difference is the threshold. In Slovakia a simplified invoice may be used up to EUR 100 including tax, and a receipt from an eKasa cash register or a fuel dispenser up to EUR 400. In Czechia the limit is CZK 10,000 including tax.
Example: a cash-register receipt for office supplies is a full tax document even without the buyer’s details. Yet where the customer needs to prove an input-VAT claim beyond doubt, it is safer to request a full invoice showing the buyer’s VAT number, so the document raises no questions during an audit.
By when must the invoice be issued?
In Slovakia a VAT payer must issue the invoice within 15 days of the supply, or of receiving a payment made before the supply (or by the end of that calendar month for advance payments). Czech rules likewise require issuing the tax document within 15 days of the supply or the receipt of an advance. In both jurisdictions the date of supply is decisive for when the obligation to declare the tax arises.
Both markets are also moving towards mandatory electronic invoicing, so getting the content of your documents right today makes that transition far smoother.
Which mistakes most often sink a document at audit?
The most frequent reason a cost is disallowed is a document that does not describe the real supply – generic wording such as “work as agreed” with no scope. Next come missing or incorrect VAT numbers, a wrong supply date, and documents issued to a different person than the one who actually received the supply.
Check documents continuously rather than only at year-end. Verify that the invoice matches the order and the delivery, that it is legible and that no mandatory detail is missing. Ordered record-keeping of this kind is exactly what keeps an audit uneventful, as we explain in our overview of professional accounting in Slovakia. Caught early, a defect can be fixed with a corrective document; found by an inspector, it usually comes with an additional assessment and a penalty.
Not sure whether your invoices and accounting documents would survive an audit in Slovakia or Czechia? We are happy to review your records and set them up without risk.
FAQ
Can I deduct VAT from a simplified invoice?
Yes. Both countries allow input VAT to be claimed from a simplified invoice within the threshold – EUR 100 (or EUR 400 for eKasa receipts) in Slovakia and CZK 10,000 in Czechia. For larger purchases it is safer to request a full invoice with your VAT number, because a clearly identified document raises no doubt at audit about who received the supply.
What if an invoice is missing a mandatory element?
The missing element must be added by a corrective document issued by the supplier, since only the issuer can amend it. If you spot the defect before an audit, you sharply reduce the risk of losing the VAT deduction. A document that does not reflect a real supply, or is issued to the wrong person, cannot be rescued by a cosmetic correction.
Are Slovak and Czech invoice rules the same?
The core content requirements are harmonised through the EU VAT Directive, so the mandatory fields are almost identical. The differences are in the detail: the legal references (Section 74 in Slovakia, Section 29 in Czechia) and the simplified-invoice thresholds (EUR 100 / EUR 400 versus CZK 10,000). The amount of tax is stated in euros in Slovakia and in Czech korunas in Czechia.