What is PDF/A?

PDF/A is a restricted form of PDF defined by ISO 19005 for long-term archiving: everything needed to display the page must be inside the file, and features that could change or break over time are forbidden. Courts, government archives and universities require it because a PDF/A file should open identically decades from now.

What PDF/A is for

An ordinary PDF file may rely on things outside itself: a font installed on the author's computer, a linked video, a script that fills in a date, or a password. Each of those is a point of failure for a document that must still open in 2056. PDF/A removes those dependencies.

The standard is ISO 19005, first published in 2005. It does not add new features to PDF; it takes the normal format and says which parts are mandatory (embedded fonts, device-independent color, metadata in XMP) and which are banned. The result is a plain, self-contained file that any PDF reader can display today and any future reader can reconstruct from the specification.

Typical places that ask for PDF/A: e-filing systems in US federal and many state courts, national archives, patent offices, university thesis repositories, and records management in regulated industries.

PDF/A-1, 2, 3 and conformance levels a, b, u

A PDF/A designation has two parts: the part number (which generation of the standard) and the conformance level (how strict).

The letters describe how much structure the file must carry:

• b (basic): the page must render reliably. Visual fidelity only. This is what most scanners and "Save as PDF/A" buttons produce.
• u (Unicode): level b plus every character must map to Unicode, so search and copy work correctly. Available from PDF/A-2 on.
• a (accessible): level u plus a logical structure tree (tagged PDF) with reading order and alt text, so screen readers can follow the document. Hardest to produce; needs tagging at creation time.

So "PDF/A-2b" means part 2, basic level, and is a sensible default when a submission system just says "PDF/A".

What is forbidden in a PDF/A file

The restrictions are what makes PDF/A trustworthy, and they are also why a converter sometimes refuses a file. A conforming file may not contain:

• Fonts that are not embedded (every glyph used must be inside the file).
• Encryption or passwords of any kind, including permission-only locks described in PDF passwords explained.
• JavaScript, launch actions and other executable content.
• Audio, video and 3D content.
• External references: links to fonts, images or color profiles outside the file. Web hyperlinks are fine.
• Transparency and layers (in PDF/A-1 only).
• Device-dependent color without an embedded ICC profile.
• Form fields that depend on XFA; AcroForm fields are allowed but must be fully specified. See PDF forms explained.

Annotations are allowed with limits: they must be visible, not hidden, and the appearance stream that draws them must be present so the reader never has to guess.

How to check if a PDF is PDF/A, and how to convert

Checking. A PDF/A file declares itself in its XMP metadata, and Adobe Acrobat shows a blue "This file claims compliance with the PDF/A standard" bar when it opens one. The declaration can be wrong, though. For real validation use veraPDF (free, open source, the industry reference validator) or Acrobat Pro's Preflight. This viewer shows document metadata under Document properties, but it does not validate conformance.

Converting. The usual routes:

1. Microsoft Word: Save As, choose PDF, click Options and tick "PDF/A compliant".
2. LibreOffice: File, Export as PDF, tick "Archive (PDF/A)" and choose the version.
3. Adobe Acrobat Pro: Save As Other, Archivable PDF, or run the PDF/A Preflight fixup on an existing file.
4. Ghostscript on the command line for batch conversion of existing files.

Scanned paper can be PDF/A too (level b, as images), and after OCR it can reach level u. Be aware that editing a PDF/A file in a general-purpose editor, including this viewer, produces an ordinary PDF: the saved file is not re-validated, so run it through a converter again if the archive requires conformance.

When you actually need PDF/A

You need it when a recipient demands it: court e-filing, a thesis repository, a government tender portal, a records retention policy. You also benefit from it for contracts and documents you expect to keep for many years, because embedded fonts and no encryption mean no surprises later.

You do not need it for day-to-day sharing. PDF/A files are often larger (full fonts, uncompressed structure) and cannot be password-protected, so for a quick draft or an invoice emailed to a client, a normal PDF is the right choice. If a file you need to archive is locked with permissions, remove the restrictions first, then convert.

Frequently asked questions