What is PDF/A? Versions, levels and PDF/A vs PDF/X vs PDF/UA
PDF/A is a version of PDF made to be opened and read exactly the same way decades from now. It is an ISO standard (ISO 19005), and courts, government agencies, universities and archives often require it for submissions. This guide explains the versions and levels, what stops a file from qualifying, and how PDF/A differs from the two other “PDF/” standards you will meet: PDF/X for print and PDF/UA for accessibility.
Updated September 28, 20266 min read
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What PDF/A requires
Everything needed to show the document must be inside the file, and nothing may depend on the outside world. In practice that means:
- Every font is embedded, so text looks the same on a computer that does not have the font.
- Colours are defined with an embedded colour profile.
- No encryption or passwords.
- No JavaScript, audio, video or links that launch other programs.
- Metadata that declares the file as PDF/A, with its version and level.
The versions: PDF/A-1, -2, -3 and -4
Each part of the standard is based on a newer version of PDF. When a portal just says “PDF/A”, PDF/A-2 is the safe choice.
- PDF/A-1 (2005): based on PDF 1.4. The strictest — no transparency, no layers. Some older systems still ask for it by name.
- PDF/A-2 (2011): based on PDF 1.7. Allows transparency, layers and JPEG 2000 images. The most widely accepted today.
- PDF/A-3 (2012): as PDF/A-2, but any kind of file can be attached. This is what e-invoice formats such as Factur-X and ZUGFeRD use to carry their XML.
- PDF/A-4 (2020): based on PDF 2.0. Newer and not yet asked for by most portals.
The levels: b, u and a
The letter after the number is the conformance level. Level b (basic) guarantees the pages look right. Level u adds that all text can be copied as real Unicode characters. Level a (accessible) also requires a tagged structure for screen readers. A requirement of “PDF/A-2b” is met by a 2b, 2u or 2a file; level b is what most submissions ask for.
What usually stops a file from qualifying
Converting is mostly about repairing these.
- Fonts that were never embedded — common in PDFs made by older office software.
- A password or editing restriction on the file.
- Attachments in a file meant to be PDF/A-2 (move to PDF/A-3 if you need them).
- Scripts or form actions left behind by the program that made the form.
Convert, then validate
Convert a PDF to PDF/A builds a PDF/A-2b or PDF/A-3b file: it embeds the colour profile, writes the declaration, removes what the standard forbids, and lists anything it could not fix. Then run Validate PDF/A to see what passes and fails. Neither step is a certificate — the reference validator used by archives is veraPDF — but together they show you what a portal will object to before you upload.
- Open Convert a PDF to PDF/A and choose PDF/A-2 (or PDF/A-3 if the file must keep an attachment).
- Read the list of what was fixed and what still blocks conformance.
- Check the result with Validate PDF/A before submitting.
PDF/A vs PDF/X vs PDF/UA
The three standards answer different questions, and one file can meet more than one of them.
- PDF/A (ISO 19005) — archiving: will this look the same in 50 years?
- PDF/X (ISO 15930) — printing: will the press reproduce exactly these colours? Used by print shops; requires print-ready colour settings. DocuGrip does not produce PDF/X.
- PDF/UA (ISO 14289) — accessibility: can a screen reader follow the document in the right order? Requires a tagged structure, a language and alternative text for images.
A court or archive wants PDF/A. A printer wants PDF/X. An accessibility requirement (such as Section 508 in the US) points to PDF/UA.