PDF/A explained: what archives, courts and authorities expect
PDF/A is the version of PDF built to open exactly the same in thirty years. What it requires, which variant to choose, and when you actually need it.
Why an ordinary PDF is not an archive
An ordinary PDF can depend on things outside itself: fonts installed on the computer that made it, the colour settings of a screen, links to other files, even scripts. Open it years later on another machine and text can shift, characters can turn into empty boxes and colours can change. For a contract, a permit, a quality record or a court file, that is not acceptable.
PDF/A — the "A" stands for archive — is the international standard ISO 19005 that closes those gaps. A PDF/A file must contain everything it needs to be displayed identically, for as long as anyone keeps it, and nothing that could change that.
What PDF/A requires
- All fonts embedded — every character is drawn from data inside the file, never from fonts on the reader's computer.
- Defined colours — an embedded colour profile, so colours do not depend on the screen or printer.
- Metadata in XMP — the title, the author and the PDF/A version itself, stored in a standard, machine-readable way.
- No encryption and no password — an archive that cannot be opened is not an archive.
- No scripts, no audio or video, no external content — nothing that runs, plays or reaches outside the file.
- Transparency and layers — forbidden in PDF/A-1, allowed but strictly defined from PDF/A-2 onwards.
You will not see most of this: a correct PDF/A looks like any other PDF. The difference shows years later, or the moment a validator checks the file.
PDF/A-1, -2, -3 and -4, and the letters a, b and u
The number is the generation; the letter is the level of conformance.
- PDF/A-1 (2005) is based on PDF 1.4. It is the strictest and the most widely accepted, but it allows no transparency.
- PDF/A-2 (2011) is based on PDF 1.7 and allows transparency, layers and JPEG 2000 images. For most new documents it is the sensible default.
- PDF/A-3 (2012) additionally lets any file be embedded — which is exactly how a Factur-X or ZUGFeRD e-invoice carries its XML.
- PDF/A-4 (2020) is based on PDF 2.0 and simplifies the levels.
- b ("basic") guarantees the visual appearance. a ("accessible") also requires a tagged structure that screen readers can follow. u ("unicode") guarantees that the text can be searched and copied.
When someone asks for "PDF/A" without saying more, PDF/A-1b or PDF/A-2b is almost always accepted. When they name a level, use exactly that one.
Who asks for it
PDF/A is required or recommended by many national archives, by courts and public bodies that accept documents electronically, in public tenders, and by organisations with long retention duties: engineering files, quality records, personnel files, contracts. It is also the safe choice for anything you must keep for seven or ten years under tax or accounting rules.
The exact requirement differs per country and per authority. When it matters, check what the receiving body specifies — the version, the level, and whether it also wants a particular file name or size.
How to check whether a file really is PDF/A
A PDF can claim to be PDF/A in its metadata without meeting the standard; the label is just a line of text. The reliable test is a validator that checks the file against ISO 19005 rule by rule. veraPDF, the open-source validator developed by the PDF Association and the Open Preservation Foundation, is the common reference, and many archives use it or something built on it.
If a file is rejected, the validator's report usually names the cause: a font that was not embedded, a missing colour profile, transparency in a PDF/A-1 file. The fix is almost always to create the PDF/A again from the source document, not to patch the PDF afterwards.
How a real PDF/A is made — and why it costs computing
A real PDF/A cannot be made by renaming a file, or by a print setting that only changes the label. The fonts must actually be embedded, the colour profile added, the metadata written and the result checked. That is why our PDF/A converter runs on our server: it converts a Word or Excel document through a complete office engine and writes a true ISO 19005 file.
That computing is the reason PDF/A is the one PDF feature on Convertburda that carries a small fee; everything else in the PDF section is free. For everyday documents you do not need PDF/A at all — to turn Word into PDF, to merge, split or compress a PDF, or to get its text back into Word, the free tools are the right choice.
Practical tips
- Make the PDF/A at the end of your process. Editing, compressing or merging it afterwards with an ordinary tool can silently break its conformance.
- Choose PDF/A-2b unless someone asks for something else.
- Keep the source document — the Word or Excel file — as well. PDF/A is for preservation, not for further editing.
- Never password-protect the archive copy. If you need a protected version to send, make it from the archive copy with the PDF lock tool and keep the open original.