What Is PDF/A? The Archive Format Courts and Universities Ask For
A court filing portal, a tender system or your university's thesis repository rejects your upload with a message about PDF/A. The file opens perfectly on your computer, so what is wrong with it? Nothing, for everyday use. PDF/A is a stricter form of PDF, and the people asking for it want to be sure the document will still open the same way in twenty years.
PDF/A in plain words
PDF/A is a version of PDF made for long-term archiving, published as the international standard ISO 19005. A PDF/A file must contain everything needed to display it, such as its fonts and colour information, and must not rely on anything outside the file or on features that could stop it opening in the future.
It is still a PDF. It opens in any PDF reader, prints normally and looks the same as the original. The difference is in what is allowed inside it.
What PDF/A leaves out, and why
Encryption and passwords are not allowed, because an archive that needs a forgotten password is lost. Links to fonts on your computer are replaced by fonts embedded in the file. Audio, video and JavaScript are not allowed, since the software that plays them may not exist later. Colours must be defined in a way any future reader can reproduce.
This is why a PDF/A file is sometimes a little larger than the original: the fonts it used to borrow from your computer now travel inside it.
The versions you will meet
PDF/A-1 is the oldest and strictest; it does not allow transparency or layers. PDF/A-2 adds support for those and for JPEG2000 images, and is the version most portals accept today. PDF/A-3 also allows other files to be attached inside the PDF, which some e-invoicing systems use. The letter after the number shows the conformance level: b (basic) guarantees the page looks right, a (accessible) also requires tagged structure for screen readers.
If a form names an exact version, such as PDF/A-1b, use that. If it just says PDF/A, PDF/A-2b is the usual safe choice.
Who asks for PDF/A
Electronic court filing in several countries, public tender and procurement portals, national archives, and universities collecting theses commonly accept or require it. Companies that keep invoices, contracts and HR records for seven years or more use it for the same reason: the file must still open when today's software is gone.
How to convert a PDF to PDF/A
Open PDF to PDF/A and add your file from your device, Google Drive, Dropbox or OneDrive, up to 260 MB. Press PDF/A and download the result; it gets -pdfa added to its name, so you keep the original alongside it. HuntPDF produces PDF/A-2 with device-independent colour.
Remove any password first with Unlock PDF, because an encrypted file cannot become PDF/A. If the document is a scan you want to be searchable in the archive, run OCR PDF before converting.
Check before you submit
Open the converted file and compare it with the original page by page, especially fonts, tables and images. If the portal states a strict version or rejects the upload again, check the file with a free validator such as veraPDF, which lists exactly which rule a file breaks. Keep your original editable file too: PDF/A is for the archive copy, not for further editing.