[{"data":1,"prerenderedAt":246},["ShallowReactive",2],{"\u002Fblog\u002Farchiving-zugferd-invoices-pdf-a3-compliance":3},{"id":4,"title":5,"body":6,"description":237,"extension":238,"lastUpdatedAt":239,"meta":240,"navigation":241,"path":242,"publishedAt":239,"seo":243,"stem":244,"__hash__":245},"blog\u002Fblog\u002F0002.archiving-zugferd-invoices-pdf-a3-compliance.md","Archiving ZUGFeRD invoices: PDF\u002FA-3 compliance requirements",{"type":7,"value":8,"toc":227},"minimark",[9,13,16,21,33,73,76,80,83,89,103,107,119,122,144,147,151,154,160,166,172,178,184,188,197,205,209,212,215,218,221,224],[10,11,12],"p",{},"ZUGFeRD invoices are not just PDFs with an XML file stapled on. The format was built with long-term archiving in mind from the start, and understanding why it uses PDF\u002FA-3 — rather than ordinary PDF — matters if you want to stay on the right side of Swiss archiving rules.",[10,14,15],{},"This post covers what Swiss law actually requires for invoice retention, why PDF\u002FA-3 is the right container format for hybrid e-invoices, and what you need to check before declaring your archive compliant.",[17,18,20],"h2",{"id":19},"what-swiss-law-requires-for-invoice-retention","What Swiss law requires for invoice retention",[10,22,23,24,28,29,32],{},"Swiss archiving obligations for business documents come from two main sources: the ",[25,26,27],"strong",{},"Code of Obligations (OR Art. 958f)"," and the ",[25,30,31],{},"Ordinance on the keeping and retention of books of account (GeBüV)",". Together they set out the rules that matter for your invoice archive:",[34,35,36,44,55,66],"ul",{},[37,38,39,40,43],"li",{},"Invoices must be retained for ",[25,41,42],{},"ten years"," from the end of the financial year in which they were issued.",[37,45,46,47,50,51,54],{},"They must be stored in a way that ensures ",[25,48,49],{},"authenticity"," (the document has not been altered since it was created) and ",[25,52,53],{},"integrity"," (you can prove it).",[37,56,57,58,61,62,65],{},"They must remain ",[25,59,60],{},"legible"," and ",[25,63,64],{},"reproducible"," throughout the entire retention period — meaning the format must still be readable in 2036 if you archived something in 2026.",[37,67,68,69,72],{},"Electronic archives must use ",[25,70,71],{},"tamper-evident"," methods, typically achieved through digital signatures, audit logs, or write-once storage.",[10,74,75],{},"What the law does not do is mandate a specific file format. It does not say \"you must use PDF\u002FA-3\". What it says, in effect, is that whatever format you choose must still be readable and verifiable a decade from now. That is where PDF\u002FA-3 earns its keep.",[17,77,79],{"id":78},"why-ordinary-pdf-is-not-good-enough-for-long-term-archiving","Why ordinary PDF is not good enough for long-term archiving",[10,81,82],{},"Standard PDF files have a problem: they can reference resources that live outside the file. Fonts, colour profiles, and embedded content can be stored externally and just referenced by the PDF. In practice this means that a PDF which looks perfect today might render incorrectly — or not at all — if those external dependencies are no longer available years down the line.",[10,84,85,88],{},[25,86,87],{},"PDF\u002FA"," is the ISO standard (ISO 19005) that fixes this by requiring full self-containment. Every resource the document needs — fonts, colour profiles, metadata — must be embedded inside the file. Nothing can be pulled in from outside at render time. The result is a file that will display identically in any compliant viewer, regardless of what software or operating system it runs on.",[10,90,91,92,61,95,98,99,102],{},"There are several PDF\u002FA versions. ",[25,93,94],{},"PDF\u002FA-1",[25,96,97],{},"PDF\u002FA-2"," both prohibit file attachments, which is a problem if you want to embed an XML invoice payload. ",[25,100,101],{},"PDF\u002FA-3"," relaxes this restriction and explicitly allows arbitrary file attachments — including machine-readable XML. That is exactly what ZUGFeRD and its French twin Factur-X use: a human-readable PDF\u002FA-3 wrapper with the structured XML embedded inside.",[17,104,106],{"id":105},"how-zugferd-uses-pdfa-3","How ZUGFeRD uses PDF\u002FA-3",[10,108,109,110,114,115,118],{},"When a ZUGFeRD invoice is generated, the invoice XML — structured according to UN\u002FCEFACT CII (Cross Industry Invoice) — is embedded into the PDF as an attachment. The attachment is named ",[111,112,113],"code",{},"factur-x.xml"," (or ",[111,116,117],{},"ZUGFeRD-invoice.xml"," in older 1.0 files) and its relationship to the PDF is declared in the document's XMP metadata.",[10,120,121],{},"The PDF\u002FA-3 conformance level ensures:",[123,124,125,132,138],"ol",{},[37,126,127,128,131],{},"The ",[25,129,130],{},"visual invoice"," (what a human reads) is permanently and faithfully renderable, with no external dependencies.",[37,133,127,134,137],{},[25,135,136],{},"machine-readable XML"," (what your ERP reads) travels with the document and cannot be separated from it accidentally.",[37,139,127,140,143],{},[25,141,142],{},"XMP metadata"," declares the profile level (MINIMUM, BASIC, EN 16931, EXTENDED) so a receiving system knows exactly what data to expect in the XML.",[10,145,146],{},"This is what makes ZUGFeRD a genuinely hybrid format rather than just a PDF with a text file attached. The two representations are linked and travel together — archive one, you archive both.",[17,148,150],{"id":149},"what-to-check-before-calling-your-archive-compliant","What to check before calling your archive compliant",[10,152,153],{},"Having PDF\u002FA-3 files is necessary but not sufficient for a compliant archive. Here is what else needs to be in place:",[10,155,156,159],{},[25,157,158],{},"Conformance validation at ingest."," Do not assume that every ZUGFeRD file you receive is actually valid PDF\u002FA-3. Suppliers make mistakes. Some generate PDFs with the ZUGFeRD label but without proper PDF\u002FA-3 conformance. Run validation — tools like veraPDF (open source) or commercial validators — when documents enter your archive, not years later when you discover a problem.",[10,161,162,165],{},[25,163,164],{},"Immutability after archiving."," Once an invoice is archived, it must not be modifiable. Write-once storage (WORM), a document management system with audit trails, or qualified timestamps all serve this purpose. A folder of files on a shared network drive with no access controls does not.",[10,167,168,171],{},[25,169,170],{},"Index and retrieval."," Swiss auditors and tax inspectors have the right to request specific invoices. Your archive must support retrieval by invoice number, supplier, date, and amount within a reasonable time. If your archive is a flat folder of ten thousand PDF\u002FA-3 files with no indexing, you technically have the documents but you will struggle to produce them on demand.",[10,173,174,177],{},[25,175,176],{},"Retention period tracking."," You need a way to know when each document's ten-year period expires. Many document management systems handle this automatically. If yours does not, a simple database or spreadsheet that records the archive date per document is better than nothing.",[10,179,180,183],{},[25,181,182],{},"Format migration policy."," PDF\u002FA-3 is a solid long-term format, but no format is guaranteed to remain accessible indefinitely. A responsible archiving policy includes a commitment to migrate documents if the format standard is deprecated or reader availability drops. In practice this is unlikely to be a problem with PDF\u002FA-3 in the near term, but having the policy written down matters for audits.",[17,185,187],{"id":186},"what-about-invoices-received-as-pure-xml-no-pdf-wrapper","What about invoices received as pure XML — no PDF wrapper?",[10,189,190,191,196],{},"If you receive invoices via ",[192,193,195],"a",{"href":194},"\u002Fblog\u002Fhow-swissdigin-extends-peppol-bis-billing-30-for-switzerland","PEPPOL"," in UBL or CII XML format with no PDF at all, the PDF\u002FA-3 question becomes moot for the original file — but you still need to satisfy the same archiving obligations. The XML must be stored in a format that remains legible and verifiable for ten years. Many organisations solve this by generating a PDF\u002FA-3 rendering of the XML on receipt and archiving both. Others use XML-native archive solutions with schema version tracking. Either approach works, as long as you can prove the document has not been altered and can be reproduced.",[10,198,199,200,204],{},"For invoices received via ",[192,201,203],{"href":202},"\u002Fblog\u002Fhow-the-ebill-network-works-a-technical-overview","eBill",", the eBill platform itself holds transaction records, but you are still responsible for your own archive. Do not assume the platform covers your retention obligation.",[17,206,208],{"id":207},"practical-next-steps","Practical next steps",[10,210,211],{},"If you are setting up a ZUGFeRD archive for the first time, the short checklist looks like this:",[10,213,214],{},"Start with a validator. Run every incoming ZUGFeRD file through a PDF\u002FA-3 validator at ingest and reject or flag non-conforming files immediately. This is far easier than auditing your archive retrospectively.",[10,216,217],{},"Choose storage that enforces immutability. A qualified document management system with audit logging is the cleanest solution. If you are using cloud storage, look for WORM-capable options.",[10,219,220],{},"Make sure your indexing covers the fields an auditor will ask for. Invoice number, supplier UID, invoice date, and net and gross amounts are the minimum.",[10,222,223],{},"Document your archiving policy. Swiss tax authorities expect you to be able to describe your process, not just produce the files. A one-page written policy covering format, storage, access controls, and retention periods will save time if you are ever inspected.",[10,225,226],{},"The ZUGFeRD format does most of the heavy lifting on the document side — PDF\u002FA-3 and the embedded XML together satisfy the machine readability and authenticity requirements cleanly. The gaps in most archives are on the process side: no validation at ingest, mutable storage, and no written policy. Fix those and you are in good shape.",{"title":228,"searchDepth":229,"depth":229,"links":230},"",2,[231,232,233,234,235,236],{"id":19,"depth":229,"text":20},{"id":78,"depth":229,"text":79},{"id":105,"depth":229,"text":106},{"id":149,"depth":229,"text":150},{"id":186,"depth":229,"text":187},{"id":207,"depth":229,"text":208},"The archival requirements for ZUGFeRD invoices under Swiss law and how PDF\u002FA-3 satisfies them.","md","2026-04-25",{},true,"\u002Fblog\u002Farchiving-zugferd-invoices-pdf-a3-compliance",{"title":5,"description":237},"blog\u002F0002.archiving-zugferd-invoices-pdf-a3-compliance","CrfqYkbQBBLYPtzsG8GWkBaNtSUJ0lQvbz6hFWWIhbs",1777105007257]