Keeping receipts digitally: audit-proof archiving for small businesses

What the law allows

Under the Code of Obligations (OR), accounting records and accounting vouchers may be kept on paper, electronically or in a comparable way, provided that they are guaranteed to match the underlying business transactions and facts and can be made readable again at any time (Art. 958f para. 3 OR). In VAT Info 16, the Federal Tax Administration (FTA) states that records kept electronically have the same evidential value as records on paper, provided that all requirements of the Accounts Ordinance (GeBüV) are met.

One exception remains: the annual report and the audit report must be kept in writing and signed (Art. 958f para. 2 OR). The signed original still goes in the paper file.

What “audit-proof” means

In everyday language people speak of audit-proof archiving. The GeBüV describes what this is about in Art. 3: records must be kept in such a way that they cannot be altered without this being detectable. On a hard disk, a network drive or in an ordinary cloud folder, a file can be overwritten or deleted without leaving a trace. Such data carriers count as alterable (Art. 9 para. 2 GeBüV), and for them Art. 9 para. 1 let. b requires additional measures:

• a technical procedure that safeguards the integrity of every document, such as a checksum;
• proof of when the document was stored that cannot be falsified, such as a timestamp;
• documented processes and retained journals.

On top of that come the general duties: recording access and keeping out unauthorised persons (Art. 8), keeping a systematic index (Art. 8), checking integrity and readability regularly (Art. 10) and being able to present the records to an authorised person within a reasonable time (Art. 6). A digital signature on every receipt, on the other hand, is not required. The details are in the guide GeBüV explained simply.

Scanning paper: how to go about it

1. Scan completely and legibly. Every page, including the back if there is something on it. Amounts, dates, VAT number and stamps must be legible.
2. Compare with the original. Before you put the paper away, check that the scan matches the original.
3. Archive promptly. The shorter the way from receipt to archive, the smaller the gap in which something can get lost or be changed.
4. Choose a durable format. The federal government’s SME Portal recommends PDF/A. Files with dynamic content are unsuitable.
5. Write down how you do it. Who scans, within what time, how quality is checked and what happens to the paper all belong in the procedure documentation (Art. 4 GeBüV).

Can the paper go in the shredder afterwards?

The law does not require you to keep the paper original after scanning. But the FTA makes clear who bears the consequences: the company that has to keep the records bears the risks of destroying the original information carrier (VAT Info 16, section 1.4.1). If a scan is incomplete or illegible and the paper is gone, you no longer have the receipt.

That is why many companies keep the paper for a while, for example until the year-end closing, and destroy it only after a spot check. Software that promises shredding is risk-free is promising too much. Either way, you should keep contracts and deeds with original signatures.

Keep digital originals digital

Whatever was created electronically is best kept in exactly that form: the PDF invoice from the email, the bank statement from e-banking, the structured file from the accounting software. For some documents this is even mandatory. According to the FTA, electronic customs assessment notices, for example, lose their status as originals if they are only printed out or kept in a different file format, and customs data transmitted electronically must be kept in electronic form (Art. 97 para. 1 Customs Ordinance). An archive should therefore store files unchanged and never convert them.

Checklist for your digital archive

• Every file has a checksum, and the checksums are themselves protected against changes.
• The time a document was added comes from an independent source.
• Nobody can delete or overwrite anything before the period has ended.
• Access, exports and deletions are recorded in a journal; the journal is kept as long as the records.
• Integrity is checked regularly.
• Everything can be exported in full and verified without the provider’s software.
• The periods are counted from the end of the business year (see retention duty).
• Procedure documentation describes how archiving is done.

How Magic Heidi Archiv does it

You drag files or a ZIP into the archive (1 GB per file or ZIP, up to 5000 files and 2 GB unpacked). Every file is stored unchanged and gets a SHA-256 checksum and an entry in a chained journal, which is given RFC 3161 timestamps from an independent authority. Until the end of the retention period, the storage in Zurich blocks any deletion. Every night everything is checked again, and there is read access and a complete export for the auditor or your trustee. A template for the procedure documentation is included.

What it does not have: text recognition, full-text search, a scanning app and interfaces to other programs. Magic Heidi Archiv keeps what you already have as a file. If you use Magic Heidi, you can add the yearly backup directly.