PDF/A is a version of PDF built for long-term archiving. The "A" stands for archival. It's an ISO standard that restricts what a PDF can contain so that the document can be reliably opened and rendered decades from now, without depending on external software, fonts, or systems that may no longer exist. If you've ever received a filing requirement that specifies "PDF/A format," this is why.
What PDF/A Restricts
Standard PDF is flexible โ it can reference external resources, embed executable code, use encryption, stream content from external sources, and rely on proprietary extensions. All of that flexibility is a liability for archiving. If a standard PDF links to an external font server that shuts down, or uses a JavaScript feature that future software doesn't support, the document may not render correctly in 20 years.
PDF/A removes those risks by prohibiting the features that create external dependencies. Specifically, PDF/A requires that all fonts be embedded in the file, bans encryption and password protection, disallows JavaScript and executable content, prohibits audio and video embedding, and requires that color be defined using device-independent color spaces.
The result is a self-contained document: everything needed to render it accurately is inside the file itself. No internet connection, no installed fonts, no third-party plugins required.
PDF/A-1, PDF/A-2, and PDF/A-3: What's the Difference?
There are multiple versions of PDF/A, each building on the last. PDF/A-1 (2005) is the most restrictive and most widely accepted for legal and government archiving. PDF/A-2 (2011) added support for JPEG 2000 compression, transparency, and digital signatures. PDF/A-3 (2012) allows embedding of arbitrary file attachments inside the PDF โ useful for attaching the source XML data to an invoice PDF, for example.
Each version also has conformance levels: /A (accessible, requires tagging for accessibility) and /B (basic, no accessibility tagging required). PDF/A-1b is the most common requirement you'll encounter โ it's the baseline that courts, government agencies, and enterprise records systems typically specify.
When You Need PDF/A vs. Standard PDF
PDF/A is required or recommended in specific contexts: legal filings in many court systems, government records submissions, regulated industry documentation (healthcare, finance), and any situation where the document needs to be reliably accessible for 10+ years. The EU, many US federal agencies, and numerous national archives have adopted PDF/A as their official archiving format.
For everyday use โ sending documents to clients, sharing reports, distributing marketing materials โ standard PDF is fine and actually preferable. PDF/A's restrictions become inconvenient when you don't need long-term archival. You can't password-protect a PDF/A, which is a problem for sensitive documents. You can't embed video, which matters for interactive presentations.
How to Create a PDF/A File
Most professional applications that export PDFs give you a PDF/A option. In Microsoft Word, go to File โ Save As โ PDF, then click Options and look for the ISO 19005-1 compliant checkbox. In Adobe Acrobat, you can save or convert to PDF/A directly. LibreOffice also supports PDF/A export from its PDF export dialog.
If you already have a standard PDF that needs to be converted to PDF/A, the conversion process checks for prohibited features and either fixes them automatically or flags them for review. Fonts get embedded, external references get resolved, and incompatible features get removed. The output is a new PDF/A-compliant file.
Can You Tell If a PDF Is PDF/A?
Yes. PDF/A files contain metadata that identifies them as such. When you open a PDF/A file in Adobe Acrobat, a blue bar appears at the top indicating the file is in PDF/A mode and that some features are disabled. Other viewers may show a similar indicator or note it in the document properties.
You can also check the document properties manually: in most PDF viewers, go to File โ Properties โ Description and look for the metadata fields that identify the PDF/A version and conformance level.
For most people, PDF/A only comes up when a specific institution requires it. When it does, the requirement usually states which version and conformance level is needed โ PDF/A-1b is the safe default if the requirement is ambiguous. Outside those specific contexts, standard PDF Tools and standard PDF format handle everything you need.