When a tax inspection lands in a company’s fifth or seventh year, the first evidence the tax authority asks to see is invoices — and for e-invoices, the question is not only “do you still have them” but “in what form do they carry value”. Many FDI enterprises keep a warehouse of PDF files and think the job is done, while the version with legal value — the XML data file with its digital signature — has been deleted by the former provider when the contract ended.
Retention period: 10 years under accounting law
An invoice is an accounting voucher, so the retention period for e-invoices follows the law on accounting document retention. Article 41 of the Law on Accounting 88/2015/QH13 requires accounting documents to be put into storage within 12 months from the end of the annual accounting period or the completion of the accounting work; among them, accounting vouchers used to record the books and prepare financial statements — the group including output and input invoices — fall in the category of retention for at least 10 years. Decree 123/2020/ND-CP (Article 6 on invoice and document preservation and storage) confirms that e-invoices are preserved and stored by electronic means and that the retention period follows accounting law. The period is counted from the starting point under accounting law (from the financial year the invoice belongs to), not from each individual issuance date — when building an internal document-destruction policy, enterprises should add a safety margin rather than destroying on the exact day 10 years elapse.
Which format carries legal value: XML is the original
An e-invoice is created as electronic data in the tax authority’s standard format (XML) and bears the seller’s digital signature (and the tax authority’s code, for coded invoices). The signed XML file is the original invoice with legal value. Other renderings — PDF files, views on the lookup portal, paper printouts — are merely representations/conversions for reading and comparison. Decree 123/2020/ND-CP (Article 7) permits converting e-invoices to paper for storage and lookup purposes, provided the conversion meets information-integrity requirements; but the converted paper copy does not replace the electronic original in relations with the tax authority. The governance consequence is clear: the enterprise’s archive must keep the full trio — the original XML file, the digital signature information with verifiability, and a readable rendering (PDF) — for every invoice, output and input alike, for the entire retention period.
Technical requirements of electronic storage
Invoice law and archives law require the storage system to ensure: data integrity (the invoice cannot be altered after issuance — content changes happen only through the traceable adjustment/replacement mechanism), the ability to look up and retrieve quickly at the request of competent authorities, the ability to produce renderings for printing/comparison, and security against unauthorised access and modification. In organisational terms, the enterprise should: (1) back up in two independent layers (the solution provider’s system plus storage infrastructure under the enterprise’s own control), because the biggest risk is total dependence on the provider; (2) write into the provider contract a clause handing over the complete XML invoice data on service termination — the exact point where many enterprises lose historical data; (3) periodically test the ability to open old data and verify signatures, because an expired digital certificate does not invalidate the invoice, but the enterprise must retain the means to prove authenticity at the time of signing; (4) for input invoices received from other suppliers, download and store the XML file from the seller’s lookup portal/link upon receipt, rather than counting on re-looking it up years later.
Frequently asked questions
How long must e-invoices be retained?
At least 10 years. Invoices belong to the group of vouchers used to record the books and prepare financial statements — documents retained for at least 10 years under Article 41 of the Law on Accounting 88/2015/QH13; Decree 123/2020/ND-CP confirms electronic storage with the period following accounting law.
Is storing the PDF of an e-invoice legally sufficient?
Not on its own. The version with legal value is the invoice’s XML data file with its digital signature; PDFs and paper printouts are renderings/conversions for reading and lookup (Article 7 of Decree 123/2020/ND-CP). The enterprise must store the original XML together with signature verification data for both output and input invoices.
What is the standard storage format for e-invoices?
The tax authority’s standard electronic data format is XML — e-invoices are created, transmitted and stored as XML files bearing the seller’s digital signature (and the tax authority’s code for coded invoices). Other formats serve only as renderings.
Can a paper printout of an e-invoice replace the electronic original?
No. Converting an e-invoice to paper under Article 7 of Decree 123/2020/ND-CP serves only document storage and lookup purposes subject to information integrity; before the tax authority, the signed XML electronic version is the invoice with legal value.
This article has been quality-reviewed by the FLAW AI Legal Council
