PDF/A is a version of PDF designed for long-term archiving. A regular PDF can depend on things outside the file, such as fonts installed on your computer, or include features like scripts and encryption that may not work decades from now. PDF/A forbids or restricts those features so that the document can be reproduced exactly the same way in the future, using only what is inside the file.
You usually need PDF/A only when someone asks for it: a court e-filing system, a government agency, a university thesis office, or an organization's records policy. For everyday sharing, a regular PDF is fine. The rest of this article explains the differences in more detail and how to produce a PDF/A file when you are asked for one.
A quick history
PDF was created in the early 1990s and became an open international standard, ISO 32000, in 2008. As PDF spread through governments, courts, and libraries, archivists noticed a problem: a PDF that opened perfectly today might not render correctly in thirty years. Fonts could be missing, color could shift, and linked content could disappear.
PDF/A, standardized as ISO 19005, was the answer. The "A" stands for archive. It is not a different file format with a new extension. A PDF/A file is still a .pdf that any viewer can open. It simply follows a stricter set of rules and declares, in its metadata, which PDF/A version and conformance level it claims to meet.
What PDF/A requires
The exact rules vary by version, but the core ideas are consistent.
Everything needed to display the document must be inside the file
- Fonts must be embedded, at least the characters actually used. No relying on the reader's system fonts.
- Color must be defined in a device-independent way, typically by embedding an output color profile, so colors can be reproduced consistently.
- Images must be contained in the file, not linked externally.
Features that threaten long-term readability are restricted
- No encryption or passwords. An archive that nobody can open in thirty years because a password was lost is not much of an archive.
- No JavaScript or executable actions.
- No audio or video content.
- No external content references that the document relies on to display.
- Transparency is prohibited in the original PDF/A-1 and allowed with conditions in later versions.
Metadata must be standardized
PDF/A requires document metadata in the XMP format, including the PDF/A identification itself. Title, author, and similar properties should be consistent between the classic document information and the XMP metadata.
The versions and conformance levels
PDF/A comes in several parts, each based on a different PDF version.
PDF/A-1
The original, published in 2005 and based on PDF 1.4. It is the strictest, with no transparency and no embedded files. Some older systems still request it specifically.
PDF/A-2
Published in 2011 and based on the newer ISO PDF specification. It adds support for transparency, layers, JPEG 2000 compression, and embedding other PDF/A files as attachments. Many organizations consider it a good general choice.
PDF/A-3
Published in 2012. It is like PDF/A-2, but allows embedding files of any format, such as a spreadsheet or XML data alongside the human-readable document. Electronic invoicing standards in some countries use this to carry machine-readable invoice data inside a readable PDF.
PDF/A-4
Published in 2020 and based on PDF 2.0. It simplifies the conformance levels and aligns with the latest PDF specification. Adoption is growing but not yet universal, so check whether your recipient's systems accept it.
Conformance levels
Within the earlier parts you will see letters after the number:
- b (basic) guarantees reliable visual reproduction. The document will look right.
- a (accessible) adds requirements for structure and tagging, such as reading order and alternative text, which help assistive technologies.
- u (Unicode), in parts 2 and 3, requires that text be mapped to Unicode so it can be searched and copied reliably.
So "PDF/A-2b" means Part 2, basic conformance. When an institution just says "PDF/A," ask which part and level they want, or check their guidelines, because a PDF/A-1a file and a PDF/A-3b file meet quite different requirements.
When you actually need PDF/A
Requirements differ by country, court, and institution, and they change over time, so always check the current rules that apply to you. Common situations where PDF/A may be required or recommended include:
- Court and legal filings. Some electronic filing systems require or prefer PDF/A for submitted documents.
- Government submissions and public records. Various agencies and national archives specify PDF/A for records they will keep permanently.
- Academic theses and dissertations. Many university repositories ask for PDF/A so the work remains readable long after graduation.
- Regulated industries. Organizations with long retention obligations may adopt PDF/A in their records policies.
- Electronic invoicing. Certain e-invoice formats are built on PDF/A-3.
Nothing here should be read as legal advice. If compliance matters, rely on the official requirements of the body you are submitting to.
When a regular PDF is better
PDF/A is not automatically "better." Its restrictions are the point. Stay with regular PDF when you need:
- Password protection or encryption, for example with our Protect PDF tool.
- Interactive features like fillable forms that the recipient will complete, scripts, or multimedia.
- Flexible editing workflows where the document is still in progress.
How to create a PDF/A file
Our tools do not currently produce certified PDF/A output, so this section describes common approaches and how our tools can help you prepare a document.
Export PDF/A from the source application
The most reliable path is to create PDF/A at the moment of export, because the authoring software has full knowledge of fonts, colors, and structure.
- LibreOffice offers a PDF/A option in its PDF export dialog, including a choice of version.
- Microsoft Word on Windows has a "PDF/A compliant" option under the options of its Save as PDF dialog.
- Professional PDF editors often include preflight and conversion features that can convert an existing PDF to PDF/A and report problems.
If you still have the original document, re-exporting it as PDF/A is almost always cleaner than converting an existing PDF.
Validate the result
A file that claims to be PDF/A is not necessarily compliant. Open-source validators such as veraPDF check a file against the PDF/A rules and list any violations. Many submission portals run a validator on upload, so checking first saves you from a rejected filing.
Preparing a document with our tools
Before converting to PDF/A, a few cleanup steps can reduce problems and improve the archived result:
- Make scans searchable. A pure image scan can be valid PDF/A, but an archive is far more useful if it can be searched. Run it through our free OCR PDF tool first so the text layer is included when you convert.
- Set accurate document properties. Archival systems often index the title, author, and subject. Use our free Edit metadata tool to set meaningful values rather than leftovers like "Microsoft Word - Document1."
- Flatten completed forms. If the archived copy should preserve filled-in values rather than stay editable, run it through Flatten PDF.
- Remove the password. If the source PDF is password protected and you are authorized to use it, Unlock PDF removes the password, since PDF/A does not allow encryption.
All of these tools run in your browser, so the document stays on your device while you prepare it.
Common pitfalls
- Assuming "Save as PDF" means PDF/A. Most default exports create regular PDFs. You have to choose the PDF/A option explicitly.
- Mixing up the version. Submitting PDF/A-3b to a system that expects PDF/A-1b can cause rejection.
- Editing after conversion. Changing a PDF/A file in a regular editor may break compliance while keeping the PDF/A label in its metadata. Revalidate after any change.
- Missing fonts in the source. If a font cannot be embedded because of licensing flags or corruption, conversion may fail or substitute a different font.
- Expecting accessibility from basic conformance. Level b ensures appearance, not structure. If accessibility is required, you need level a or a separately tagged document.
Key takeaways
- PDF/A is ISO-standardized PDF for long-term archiving, with fonts, colors, and metadata self-contained.
- It restricts encryption, scripts, multimedia, and external dependencies.
- Choose the part (1, 2, 3, or 4) and conformance level your recipient specifies.
- Create PDF/A from the source application when possible, then validate it.
- Prepare documents with OCR, accurate metadata, and flattened forms before conversion.
PDF/A can sound intimidating, but in practice it is a checklist. Know which variant is requested, export with the right setting, validate the file, and your document should remain readable long after the software that created it is gone.