PDF/A Explained: What It Is and When You Need It

By PDFwarp · · 5 min read

PDF/A is a restricted PDF format built for documents that must still open correctly in 20 years. Here's what it locks down and who actually needs it.

If someone has ever bounced your filing back with "please resubmit as PDF/A," you've hit a format most people never encounter until a court, a government agency, or a records-management policy requires it. Here's what PDF/A actually is, what a regular PDF export won't give you, and how to tell if you're in a situation that needs it.

The problem PDF/A solves

A regular PDF is designed to look right today, on your software. It can reference fonts installed on your system instead of embedding them, link out to external files, run JavaScript, and be encrypted. All of that is fine for a document someone opens next week. It's a real risk for a document someone needs to open in 2046: the referenced font might not exist anymore, the external link is dead, the encryption might be tied to software that no longer runs, and older JavaScript can behave unpredictably in a modern PDF reader — or simply fail to run at all.

PDF/A (ISO 19005, first published in 2005, with PDF/A-1, -2, and -3 revisions since) is a restricted subset of the PDF spec built specifically to close those holes. A valid PDF/A file:

The tradeoff is that PDF/A files are typically a little larger than an equivalent regular PDF (because every font is embedded rather than referenced), and once a document has some of the restricted features, it has to be explicitly converted or re-exported to comply.

Who actually needs this

PDF/A shows up in a specific, recurring set of situations: government and legal filings (many courts require PDF/A specifically for electronic filing systems), regulatory and compliance records that must be retrievable and unaltered for a defined retention period, university thesis and dissertation submissions, and institutional archives (libraries, museums, records offices) preserving documents for the long term. If none of those describe what you're doing, you almost certainly don't need PDF/A — a regular PDF from any standard export is fine, and PDF/A's restrictions (no encryption, no interactive forms, no embedded media) would just get in the way of things a normal document is allowed to do.

A useful gut check: if the requirement is "this document must still open correctly and look identical in several decades, regardless of what software exists then," it's a PDF/A situation. If the requirement is "send me a document," it isn't.

PDF/A vs. just exporting to PDF

The confusion usually starts because most everyday tools — Word's "Save as PDF," a browser's print-to-PDF, most online converters — produce a standard PDF, not a PDF/A file, even though the result looks identical on screen. The restrictions PDF/A enforces (embedded fonts, no external references, no encryption) aren't things you can verify by eye; a file can look completely normal and still fail PDF/A validation because a font wasn't embedded or a color profile is missing. That's why an agency asking for PDF/A specifically will usually reject a regular PDF even if it opens and reads fine — it's not what was asked for, and it won't pass their format validator.

A note on PDFwarp specifically: Office → PDF converts Word, Excel, and PowerPoint files to standard PDF with fonts and layout preserved. It does not currently produce PDF/A-compliant output as a distinct format option. If you specifically need PDF/A and the tool doesn't offer it, dedicated PDF/A conversion software (or your document management system's export option, if it has one) is the right call for now — don't submit a regular PDF and hope it passes a PDF/A validator, because it generally won't.

How to check if a file you already have is PDF/A

Most desktop PDF readers with an advanced view (Adobe Acrobat, for instance) will show the PDF/A conformance level in the document properties if one is declared. If you don't have access to that, the practical test is simpler: try opening the file with all fonts you have installed removed or in a viewer on a different machine — if text reflows or substitutes into a different font, it wasn't relying on embedded fonts, which is a strong sign it isn't PDF/A compliant, since real PDF/A files embed everything by definition.

FAQ

Is PDF/A just a regular PDF with a different file extension?

No — same ".pdf" extension, but a genuinely restricted internal structure. The difference is in what the file is allowed to contain (no encryption, no external references, fully embedded fonts), not in the file extension or how it opens.

Can I convert an existing PDF to PDF/A myself?

Sometimes, if the original doesn't use any of the disallowed features (JavaScript, encryption, unembedded fonts) — but if it does, those features have to be stripped or replaced, which can mean re-exporting from the source document rather than patching the PDF after the fact.

Does PDF/A support fillable forms?

PDF/A-2 and PDF/A-3 support a form of interactive forms, but with restrictions regular AcroForms don't have. If your workflow depends heavily on fillable fields, check the specific PDF/A version your recipient requires before assuming it'll work the way a normal fillable PDF does.

Will my PDF/A file be bigger than a normal PDF of the same document?

Usually somewhat, mainly because every font is fully embedded rather than referenced from the system. For a text-heavy document this difference is typically small — a few hundred KB, not multiples of the file size.

For more on what actually determines a PDF's file size day to day, see How to Compress a PDF Under 1 MB for Email.