"How long do I keep this?" sounds like one question with one number for an answer. It is actually several questions stacked on top of each other, because the same invoice is simultaneously a tax record, evidence in a potential contract dispute, and proof of purchase behind a warranty. Each of those roles runs on its own clock, and they rarely expire together.
The workable answer is to stop looking for the single correct number and instead identify the longest clock that applies to you, then set one policy at or beyond it. Storage is cheap; reconstructing a destroyed record during an audit is not.
Three clocks on the same document
The tax clock is the one most people mean. It is set by how far back your tax authority can open an assessment, and it is usually counted not from the invoice date but from the end of the tax year or accounting period the invoice belongs to — which quietly adds up to a year to the real-world figure.
The contract clock runs on the limitation period for bringing a claim. If a client can sue you over work done four years ago, the invoice, the scope it references and the correspondence around it are your evidence. This period is frequently longer than the tax one and is the clock most small businesses forget entirely.
The asset clock applies to things you bought rather than sold. A purchase invoice is the proof of what you paid and when, which matters for depreciation schedules, for warranty and insurance claims, and — where capital assets carry special adjustment rules, as they do under several VAT systems — for a period substantially longer than the ordinary one.
How the periods differ
Retention periods are national and they vary widely, from a few years to a decade. The table gives a sense of the spread rather than a compliance answer — thresholds and counting rules change, and several countries have adjusted theirs recently. Confirm your own position with your tax authority or accountant.
| Jurisdiction | Commonly cited period | Notes on counting |
|---|---|---|
| United Kingdom | Six years for VAT records | Longer for capital goods; counted from the end of the relevant period |
| United States | Three to seven years depending on the record and circumstance | The IRS ties the period to the limitation window for the return, which some situations extend |
| Germany | Commonly cited at eight to ten years for accounting documents | Counted from the end of the calendar year in which the document was created; recently reformed, so verify the current figure |
| EU generally | Member states set their own, frequently in the five to ten year range | The VAT Directive leaves the period to national law |
Keeping invoices digitally
Digital storage is accepted essentially everywhere, but acceptance comes with conditions rather than as a blanket permission. The recurring requirements are integrity, legibility and availability: the record must be unaltered, readable throughout the retention period, and producible on request within a reasonable time.
Integrity is the one that catches people. A folder of PDFs anyone can overwrite is weaker evidence than an archive with immutability or a clear audit trail. Legibility is a slower problem — a proprietary format from a discontinued product can become unreadable long before the retention period expires, which is why plain, open formats age better than clever ones.
Two further points matter under e-invoicing mandates. Where the original invoice was a structured file, the structured file is generally the record — a PDF rendering of it is a convenience copy, not a substitute. And where records are stored on servers in another country, some jurisdictions impose conditions on offshore storage or on guaranteed access from within the country.
Setting one policy you will actually follow
A retention policy that requires per-document judgement will not survive contact with a busy year. The practical approach is to find the longest period that plausibly applies to your business, round it up, and apply it uniformly to everything.
For most small businesses that produces a policy in the region of seven to ten years, which comfortably covers ordinary tax and contract exposure in most jurisdictions. Keep sales and purchase invoices together with the records that give them meaning — contracts, delivery evidence, remittance advice and the bank data that proves settlement — because an invoice alone often fails to answer the question an auditor actually asks.
Then automate it. Annual archive folders, a backup that is genuinely separate from your working files, and a documented rule for what gets deleted when. The goal is that answering "can you produce the March invoice from six years ago?" takes minutes and not a weekend.
Common Mistakes
Counting from the invoice date
Most regimes count from the end of the tax year or calendar year the invoice falls into, not from the date on the document. Assuming otherwise can leave you deleting records up to a year early.
Keeping the invoice but not its context
An invoice proves an amount was billed. The contract, the delivery note and the bank record prove what it was for and that it settled. Auditors ask about the whole chain, so archive the chain.
Relying on a single cloud account as the archive
An account you can be locked out of, or that a subscription lapse can close, is not an archive. Keep an independent copy in an open format that survives changing software.
Discarding the structured original after printing a PDF
Where an e-invoicing mandate applies, the structured file is usually the legal record. A printed or rendered version is a convenience copy and may not satisfy an inspection on its own.
Frequently Asked Questions
Do I need to keep paper originals?
In most jurisdictions no — digital copies are acceptable provided integrity, legibility and availability are maintained for the full period. A few countries retain narrow exceptions for particular documents, so check locally before running a shredder over an archive.
How long should I keep invoices for equipment I bought?
Longer than the ordinary tax period, as a rule. Purchase invoices for capital assets support depreciation over the asset’s life, back warranty and insurance claims, and in several VAT systems fall under extended adjustment periods. Keeping them for the life of the asset plus your normal retention period is a common and defensible approach.
Can I delete invoices from a client I no longer work with?
Not before the retention clock expires. The obligation attaches to the record and the period, not to whether the relationship is ongoing. Ending a client relationship changes nothing about how long their invoices must survive.
What happens if I cannot produce an invoice during an audit?
Typically the deduction or the input tax claim it supported is disallowed, and penalties may follow depending on the jurisdiction and on whether the failure looks careless or deliberate. The burden of proof generally sits with the taxpayer, which is the entire reason retention rules exist.
Sources & Further Reading
- Record keeping (VAT Notice 700/21) — HM Revenue & Customs
- How long should I keep records? — Internal Revenue Service
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