Accounting documents: what they must contain and how long to archive them

Accounting documents are the basic building block of all accounting records. Without the correct details, a document may be invalid and the related cost disallowed, so it pays to know the rules and follow them from the start.

What an accounting document is

An accounting document is a verifiable record of a business transaction. It proves that the event actually took place and serves as the basis for booking it.

They include invoices, cash vouchers, internal documents, bank statements and payroll reports. Each of them must be reliable so that the accounts can use it as supporting evidence.

Mandatory details

For a document to be valid, it must contain the details required by law. Missing details are one of the most common causes of problems during an audit.

• the designation of the document and its number
• a description of the transaction and its parties
• the monetary amount, or the quantity and price
• the date the document was prepared and the date the transaction took place
• the signature records of the persons responsible

Electronic and paper documents

A document can be in paper or electronic form; both are equivalent provided that the authenticity of origin, the integrity of content and legibility are guaranteed.

Many companies are now moving to fully electronic archiving, which saves both space and time when searching for documents. The important thing is to set up the process correctly so that the documents meet the requirements for the entire retention period.

How long to archive documents

Accounting documents must be kept for the period laid down by law, which differs according to the type of document. Some documents, for example those relating to taxes or payroll, have significantly longer periods.

Check the specific retention periods for the type of document in question, as they may differ and change over time. Shredding documents too early can cause problems during an audit, so it is better to err on the side of caution.

Practical archiving tips

Keep documents organised by period and type so that you can find them quickly. A clear system saves a great deal of time, especially during an audit or when checking transactions retrospectively.

• logical sorting by year and by area
• regular backups of electronic data
• protection against unauthorised access and loss

Types of accounting documents

In practice, you will come across several types of documents, each with its own specific features. External documents arise from dealings with other parties; internal documents are used to record transactions within the company.

Knowing these differences is useful, because each type has its own rules for how it is prepared and checked. An incorrectly prepared internal document tends to be just as problematic as a missing purchase invoice.

• purchase and sales invoices
• cash receipt and cash payment vouchers
• internal documents for reclassifications and corrections
• bank statements and payroll documents

Documents and tax audits

In a tax audit, documents are the key evidence. If you cannot support a cost with a valid document, you risk having it disallowed and additional tax assessed.

That is why it pays to give documents attention on an ongoing basis rather than retrospectively. Orderly records are the cheapest protection against unpleasant surprises.

Corrections and cancellations of documents

In practice, you cannot avoid situations where a document needs to be corrected or cancelled. However, an accounting document is never overwritten or deleted in a way that loses the original information.

A correction is made in a verifiable way, for example with a correcting or cancellation document that clearly refers to the original transaction. This preserves a complete trail, and during an audit it is clear what was changed and why.

Related articles: Depreciation of assets: straight-line vs. accelerated depreciation, Financial statements of an s.r.o.: what they contain and when to file them, Low-value and fixed assets: how to account for them correctly.

Frequently asked questions

Is an invoice received by e-mail a valid accounting document?

Yes, an electronic document is equivalent to a paper one, provided that the authenticity of its origin, the integrity of its content and its legibility are ensured throughout the archiving period. What matters is that the document is stored correctly and backed up regularly.

What if an accounting document is lost?

A missing document should be replaced as soon as possible, for example by requesting a duplicate from the supplier. During an audit, you must be able to prove the transaction; otherwise the cost may be disallowed and a penalty imposed.