Here is the secret nobody puts at the top of the page: these three are not competitors. They are three different kinds of things: a specialist standard, a general rulebook, and a law, and once you see which is which, the whole alphabet soup sorts itself out in about five minutes. Let’s sort it.

Three Names, Three Different Jobs

Think of it like building safety. The law says your building must be safe for everyone. The building code spells out what “safe” means, ramp angles, door widths, handrail heights. And for specialized structures, there are specialist codes with extra detail the general code doesn’t cover.

Document accessibility works the same way. Section 508 is the law, it says federal digital content must be accessible. WCAG is the general code, the detailed rulebook that laws point to when they need to define “accessible.” And PDF/UA is the specialist code, a standard written specifically for PDF files, with a level of PDF detail that WCAG never gets into.

The Quick Comparison

PDF/UA, in Plain English

PDF/UA stands for PDF Universal Accessibility. It is an international standard, officially ISO 14289, that defines, in precise technical terms, what a fully accessible PDF looks like on the inside. Where WCAG says “content needs structure,” PDF/UA says exactly which tags a PDF must contain, how they must nest, how reading order must flow, and dozens of other PDF-specific rules.

If you have read our guide to what a tagged PDF is, here is the short version: PDF/UA compliance means the tags are not just present, they are complete, correct, and consistent, top to bottom. It is “tags done right,” written down as a formal checklist that software and auditors can verify against.

Who actually asks for it? Procurement teams, government contracts, large institutions, and increasingly European organizations, since EU accessibility rules lean on it for documents. In the U.S., PDF/UA usually shows up by name in a contract clause, and when it does, it is not a suggestion.

WCAG, in Plain English

WCAG, the Web Content Accessibility Guidelines, is the closest thing digital accessibility has to a universal rulebook. It was written for the web, but its requirements apply to documents too: text alternatives for images, sufficient color contrast, meaningful structure, content that works for assistive technology. A PDF posted on your website is web content, and WCAG treats it that way.

WCAG comes in versions (2.0, 2.1, 2.2) and levels (A, AA, AAA). When a law, a lawsuit, or a client says “accessible,” they almost always mean WCAG Level AA. That makes WCAG the default benchmark for nearly everyone, if no one has named a specific standard, WCAG AA is the safe assumption.

The catch: because WCAG was written for everything, it sometimes lacks PDF-specific detail. It tells you a document needs a logical structure; it does not tell you exactly how PDF table tags should nest. That is the gap PDF/UA fills.

Section 508, in Plain English

Section 508 is different from the other two in one crucial way: it is not a standard at all. It is a United States federal law, part of the Rehabilitation Act, that requires federal agencies to make their electronic content accessible, and to buy accessible products and services.

So what does “accessible” mean under Section 508? Since its 2017 update, the law answers that question by pointing at WCAG: federal content must meet WCAG 2.0 Level AA. In other words, Section 508 borrows its technical rules from WCAG rather than writing its own. The law supplies the “must”; WCAG supplies the “how.”

If you sell software, services, or content to federal agencies, Section 508 reaches you too, agencies are required to buy accessible, and they verify it during procurement by asking vendors for an accessibility report. That report is the ACR (often called a VPAT), which we prepare through our VPAT and ACR service.

So Which One Applies to You?

Match your situation to the scenarios below and the answer usually falls right out:

• • You work for or sell to a federal agency. Section 508 applies, which means WCAG 2.0 AA for your documents, and expect to be asked for a VPAT/ACR during procurement.

• • You are a state or local government. The Department of Justice Title II rule requires WCAG 2.1 AA, and it explicitly covers documents; PDFs count under Title II, with deadlines in 2027 and 2028.

• • A contract or client specifically names PDF/UA. Then PDF/UA it is, your documents need full, verified conformance to the ISO standard.

• • Everyone else, businesses, nonprofits, schools. WCAG Level AA is your benchmark. It is what ADA lawsuits cite, what accessibility policies reference, and what buyers assume.

And now the genuinely good news, which deserves its own paragraph: the work behind all three standards is the same work. Correct tags, logical reading order, meaningful alt text, properly structured tables and forms, that is the whole job, whatever name is on the requirement. A PDF remediated properly to PDF/UA meets WCAG for documents and satisfies Section 508 at the same time. You are not choosing between three projects; you are doing one project that answers three names.

That is exactly how our manual PDF remediation service works: humans fix the document once, to the strictest applicable bar, and every standard on this page is covered. If you want to know what that costs, our PDF remediation pricing guide lays out real numbers.

One Warning Before You Buy a “Compliance” Tool

Plenty of software promises one-click PDF/UA compliance. Automated checkers are useful, they catch missing tags and structural errors fast, but they cannot judge whether your alt text makes sense, whether the reading order matches the meaning of the page, or whether a table actually communicates what it shows. Those judgment calls are most of what accessibility is. We wrote about why automated PDF checkers miss the most important errors if you want the full picture before trusting a green checkmark.

Frequently Asked Questions

Is PDF/UA required by law in the United States?

Not directly. U.S. laws point to WCAG rather than PDF/UA. But PDF/UA becomes binding the moment a contract requires it, and it is the recognized best practice for documents worldwide. Meeting it also means you have comfortably met the WCAG document requirements U.S. laws actually cite.

What is ISO 14289?

ISO 14289 is the official designation for PDF/UA, the same standard under its formal international name. If a contract references ISO 14289, ISO 14289-1, or PDF/UA-1, they are all pointing at the same set of requirements for accessible PDF files.

Can one PDF meet PDF/UA, WCAG, and Section 508 at the same time?

Yes, and that should be the goal. The three overlap almost completely for documents. A PDF remediated to PDF/UA standards, with human-verified tags, reading order, and alt text, satisfies WCAG’s document requirements and Section 508’s technical rules in one pass.

Get One Answer Instead of Three

If you arrived here holding a compliance email and a folder of PDFs, here is your path: figure out which scenario above is yours, then fix the documents once, properly. Our PDF accessibility workspace shows exactly how we take files from “we’re not sure” to verified compliant, whichever standard is doing the asking.

Send us a document through the free audit and we will tell you where it stands against all three standards, in plain English, with our pricing published up front. Three names, one job. Let’s get it done.