Invoice Retention Periods in Portugal: The 10-Year Rule and What Happens If You Lose One

Understanding invoice retention in Portugal is the kind of thing most accountants feel confident about — until an inspector asks for a specific document from six years ago and the file isn't there. The 10-year rule sounds simple. The digital invoice archive requirements that govern how you store those documents are less simple. Our SAF-T Portugal guide covers the monthly reporting that ties directly to the same records.

This guide is for the accountant who needs a clean answer on three questions: how long you must keep invoices in Portugal, in what format, and what to do when something goes missing.

How Long You Actually Have to Keep Invoices

The headline number is 10 years, but that's not the whole story. Different rules cite different articles, and the longest applicable period wins.

• VAT Code (CIVA), Article 52 — sets the general invoice and accounting-record retention at 10 years for books, records, and supporting documents (extended from 5 in 2019, then confirmed in later reforms).
• Corporate tax (CIRC) — aligns at 10 years for accounting records that support declared income and deductions.
• Commercial Code (Código Comercial), Article 40 — also pushes commercial books and correspondence to 10 years.
• Personal income tax (CIRS) — lower in most cases, but when invoices support a deduction or a real-estate capital gain the same 10-year horizon applies in practice, because those records may be needed for cross-checks.
• Social security and labour — separate rules, but the documents you care about (payroll, contracts) have their own long horizons.

The count starts from the end of the tax year the document belongs to, not from the invoice date. A January 2026 invoice is, for retention purposes, a 2026 document — the clock starts on 31 December 2026 and runs to 31 December 2036.

Keep that detail in mind when you plan a migration or a purge. Throwing away 2015 invoices in January 2026 is wrong; they are still inside the window until the end of 2025 has passed, and in practice you wait until after the year-end closure to be safe.

What AT Actually Accepts as a Digital Copy

This is where accountants lose sleep. The short version: AT accepts digital archiving on its own — paper is not required — but the digital copy must meet specific conditions. The long version lives in Decreto-Lei 28/2019 and the Portaria that implements it.

The non-negotiable requirements are three:

1. Integrity. You must be able to prove the document has not been altered since it was issued. PDF/A is the recommended format because it locks fonts and content. Hashing the file and keeping the hash in your accounting record is the stricter, defensible option.
2. Authenticity. The origin of the invoice must be identifiable. For e-invoices this means a qualified electronic signature or EDI with a contractual guarantee. For a supplier PDF received by email, you need a reliable audit trail — typically the original email preserved — or a manual control that links the invoice to the supplier order and payment.
3. Legibility. The document must be human-readable for the full 10 years. That means no proprietary formats that may not open in 2036, no scans so compressed they lose fields, no encryption without the keys stored alongside.

What AT does NOT require:

• A specific certified archive vendor. No "SEF-approved" list exists for this.
• Paper originals kept in parallel, once you have a compliant digital archive.
• A single software product. A structured folder in Google Drive plus PDF/A files plus a register satisfies the rules, provided integrity and authenticity are demonstrable.

What AT will ask for in a real inspection:

• The original invoice PDF (not a scan of a printout if a PDF existed).
• The accounting entry that references it.
• The payment record that matches it.
• The SAF-T line where the invoice appears.

If all four line up and the PDF is clearly the original, the conversation is short. If any one is missing or mismatched, the conversation gets longer.

The Real Risk: What Happens When a Document Is Missing

Most accountants overestimate the penalty for a missing invoice and underestimate the collateral damage. Here is the actual cascade.

First, the deduction is denied. Under CIVA Article 19, input VAT is only deductible with a valid invoice. No invoice, no deduction. AT recalculates VAT for the period, charges the difference, and adds interest at the legal rate. For corporate tax, the expense is also disallowed, so the client pays IRC on income that was offset by a real cost — a double hit.

Second, there's a fine. RGIT (General Regime for Tax Infractions) Articles 113 and 117 cover this. Missing or inadequate records attract fines from a few hundred euros to several thousand per infraction. It is rarely one invoice — when an inspector finds a hole, they look for more.

Third, credibility erodes. If the archive has one missing document, the inspector assumes there are others. The scope of the inspection widens. Other clients of the same accountant sometimes get a closer look.

The penalty for willingly destroying required records is heavier and can reach criminal territory under some readings of the Commercial Code and RGIT. That is not the common case — the common case is a lost file, not a destroyed one — but it is worth knowing the line.

What to Do When You Actually Lose One

Step by step, because this matters more than the theory.

1. Confirm it is really missing

Check every channel before declaring it lost. Email search for the supplier's sending address, the shared Drive folder for misplaced files, the downloads folder on the person who usually handles it, and the supplier portal if they have one. A surprising share of "lost" invoices are just misfiled.

2. Request a duplicate from the supplier

A "segunda via" from the supplier is the cleanest fix. By Portuguese commercial practice, suppliers can issue a duplicate referencing the original invoice number and date. The duplicate is a valid document for the deduction and for SAF-T purposes, though you should keep both the duplicate and any partial record of the original (email fragment, payment record) to show continuity.

If the supplier has closed or refuses, the document is genuinely lost, and the path changes.

3. Check e-fatura

For invoices the supplier communicated to AT, the invoice appears on the Portal das Finanças e-fatura portal. You can usually download a summary record. This is not the original invoice, but it is evidence the invoice existed and that AT has it in their own records. It strengthens any later reconstitution.

4. Reconstitute from payment and contract records

Build a parallel file: the bank statement line showing the payment, the supplier agreement or order, any earlier invoices from the same supplier establishing the pricing, and a written note explaining the gap. This does not fully substitute for the invoice, but in a tolerant inspection it shifts the discussion from "you have nothing" to "you have everything except the PDF."

5. Document the loss internally

Write a one-page internal note on the date, the reason, and the steps taken. Keep it with the reconstitution file. If the loss later triggers a question, you show the inspector you didn't ignore it — you investigated and recorded it.

6. Decide whether to reverse the deduction proactively

In some cases the cleanest move, especially near a year-end, is to reverse the VAT deduction and the expense proactively, submit a corrective SAF-T or declaration, and pay the small correction. This closes the exposure and avoids a future inspection widening into other periods. It is a judgement call, and it depends on the amount, the client profile, and the proximity to a deadline.

A Practical Retention Checklist

1. Confirm with each client which document categories are in scope (AP invoices, AR invoices, credit notes, transport documents, payroll, contracts). Different categories have different horizons.
2. Settle on one digital format: PDF/A as the archive standard, originals kept if already digital.
3. Write the retention rule into the client onboarding document: "invoices from year N are retained until 31 December (N+10) and purged in Q1 of (N+11)."
4. Set the purge task as a recurring January job on every account. Purging has to be deliberate — drifting into keeping everything forever creates a different legal exposure under GDPR.
5. Check integrity annually. A random sample of 10 files from each year, opened and visually confirmed, catches storage corruption early.
6. Keep the register — the link between the PDF, the accounting entry, the payment, and the SAF-T line — as first-class data. The register is what an inspector asks for first.
7. Back up in two places with different failure modes. Google Drive plus a local encrypted copy, for example. Never one location only.

A clean retention system does three things at once: it keeps you inside the 10-year rule, it makes AT inspections short instead of long, and it gives you a defensible answer when a document goes missing. Most accountants we work with adopt something close to the checklist above within a month. The ones who don't usually discover the gap at exactly the wrong moment — when an inspector is already on the line.

If you run the archive for dozens of small business clients, automated ingestion and SAF-T-linked storage stop being a nice-to-have. See our practical guide for accountants and the companion piece on digital invoice archiving in Portugal for the full workflow.

Frequently Asked Questions

Does the 10-year rule apply to digital invoices?

Yes. Whether stored physically or digitally, invoices must be retained for 10 years. The digital copy must be accessible and unaltered throughout the retention period.

When does the 10-year period start?

From the end of the tax year in which the invoice was issued. An invoice issued in March 2024 must be kept until at least December 31, 2034.

What happens if I can't produce an invoice during an AT audit?

Missing invoices result in disallowed VAT deductions for that period and a fine. Each missing document can attract a penalty of €150–€3,750 depending on the value and severity.

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