The answer in advance: PDF/A is available in conformity levels B, U and A. Level B secures the appearance, Level U additionally the Unicode text, Level A the tagged document structure. Every subsequent PDF/A conversion — whether with Adobe Document Services, Ghostscript or other tools — creates Level B. Level A is only created in the source application.
What PDF/A is needed for
PDF/A is the ISO 19005 standard for long-term archiving. A PDF/A document must be self-sufficient: all fonts are embedded, color spaces are defined via ICC profiles, JavaScript and encryption are prohibited. If you open the file twenty years from now, you will see exactly what was created today.
Table of Contents
In SAP projects, we encounter the requirement in three places. Firstly, in the case of e-invoices: ZUGFeRD and Factur-X embed the XML invoice data in a PDF/A-3. Secondly, in the case of technical documentation according to VDI 2770, where customers such as BASF require the manufacturer’s documents as PDF/A. Thirdly, in the audit-proof storage of documents in the archive. In all three cases, the same question arises: What level of conformity is required — and what can your own system landscape even provide?
PDF/A-1 to PDF/A-4: the standard parts
The number after the slash denotes the standard part, not the quality. The parts do not replace each other, but are based on different PDF versions and allow different functions.
| Standard part | Base | Essential feature | Typical use |
|---|---|---|---|
| PDF/A-1 (2005) | PDF 1.4 | Strictest part, no transparency, no JPEG2000 | Legacy Archive Systems |
| PDF/A-2 (2011) | PDF 1.7 | Allows transparency, layers, embedded PDF/A attachments | Default choice for scans and documents |
| PDF/A-3 (2012) | PDF 1.7 | Allows arbitrary embedded files | ZUGFeRD, Factur-X, hybrid formats |
| PDF/A-4 (2020) | PDF 2.0 | No longer knows a/b/u levels, instead variants f and e | New systems, still not very common |
For daily work, this means that a PDF/A-3 is not “better” than a PDF/A-2. It can only embed third-party files — which is exactly why ZUGFeRD decided to do this.
Level A, you and B: the real difference
More interesting than the standard part is the lowercase letter behind it. It indicates the level of conformity and answers the question of how much a program — or a screen reader — can read from the document.
| Level | Stands for | Guaranteed | Reachable by |
|---|---|---|---|
| B | Basic | Visual reproducibility: The document looks the same all the time | Any PDF/A conversion |
| U | Unicode | In addition, all text is Unicode-mapped, so it can be reliably searched and copied | Conversion if the font mappings are clean |
| A | accessible | Additional: Tagged structure — headings, reading order, table logic, alt texts | Only the generating application (or manual tagging) |
The leap from you to A is not a gradual, but a categorical one. Tags are structural information: they mark what a heading is, in what order a two-column layout is read, and what can be seen on an image. This information is simply not included in a finished, untagged PDF. A converter cannot therefore “uncover” them — it would have to guess them.
Why conversion tools only produce level B
This limit is not a weakness of individual products, but lies in the principle of conversion. Two examples from our project practice:
Adobe Document Services (ADS), the form server in SAP landscapes, offers the task ConvertPDF2PDFA for subsequent conversion. It only accepts PDF/A-1b, PDF/A-2b and PDF/A-3b as target formats. The A-levels don’t even appear in the conversion interface — Adobe knows why. The situation is different when it comes to rendering : If you create an Adobe form directly from SAP, you can activate tagged output, because the structure information there comes from the form template.
Ghostscript, the most common free tool, also only knows the -dPDFA=2 B-path. The result validated as PDF/A-2b, nothing more. We have tested this extensively as part of a VDI 2770 project: color profiles, transparencies and CMYK old stocks can be reliably cleaned up — no tags are created.
That leaves the subsequent auto-tagging, for example in Adobe Acrobat Pro. It delivers formally valid Level A files, but works heuristically: The program advises headings at the font size, reading sequences at the position. This works well for simple documents, but for tables, forms and scans, a structure is created that passes through the validator, but is of little help to a screen reader user. If you need real Level A, create it in the source — for example, via tagged export from Word or InDesign.
When Level B is enough — and when it’s not
The good news is that in most archiving and exchange scenarios, Level B is the accepted status. For years, the PDF Association has listed Level B as the level that can be achieved without interfering with document creation; accordingly, it is the norm in practice.
In the case of manufacturer documentation according to VDI 2770, the guideline recommends Level A, but validators classify Level B as a warning, not as an error. This is consistent: a scanned factory certificate from the steel mill will never have a meaningful tag structure. Our recommendation to suppliers is therefore to clarify the warning openly with the buyer instead of spending time on heuristic post-tagging.
The case is different with consumer bills. The Accessibility Strengthening Act (BFSG) has been in force since 28 June 2025. It obliges providers of certain B2C services — such as telecommunications, banks, energy suppliers and e-commerce — to also provide accompanying documents in a barrier-free manner. For PDF invoices, this means: tagged files according to PDF/UA (ISO 14289). The standard can be combined with PDF/A-3, so a ZUGFeRD invoice can also be barrier-free. If you generate mass invoices to consumers from SAP, you should now check the render route for this — with pure B2B invoices and XRechnung, this pressure does not exist.
Frequently asked questions about PDF/A conversion
What does PDF/A Level B mean?
Level B (basic) guarantees that a PDF will look exactly the same as it did on the day it was created: all fonts embedded, colors defined, no external dependencies. It is the stage that any PDF/A conversion can reach, and in archiving practice it is the standard case.
Is it possible to convert a PDF to PDF/A Level A afterwards?
Formally, yes, but only to a limited extent in terms of content. Level A requires a tagged document structure that a converter cannot read from the page image. Tools such as Adobe Acrobat Pro generate tags afterwards using heuristics — the result is validated, but the quality of the reading order and alternative texts remains manual work. Server-side converters such as Adobe Document Services or Ghostscript only offer the B-levels.
What PDF/A level does ZUGFeRD require?
ZUGFeRD and Factur-X require PDF/A-3 because the XML invoice data is embedded as an attachment. The standard does not prescribe a level of conformity; in practice, Level B is used. Tagged invoices according to PDF/UA only become relevant for consumer invoices through the Accessibility Strengthening Act.
What PDF/A level does VDI 2770 require?
The VDI 2770 guideline recommends PDF/A with Level A for manufacturer documentation. Validators such as the Digital Data Chain Consortium therefore report Level B as a warning, not as an error. In industrial practice, recipients accept Level B because a large proportion of documents — such as scanned factory certificates — cannot technically reach Level A at all.
What does the BFSG require for PDF invoices?
The Accessibility Enhancement Act has been in force since 28 June 2025 and obliges providers of certain consumer services to also provide accompanying documents such as invoices in a barrier-free manner. The technical standard for this is PDF/UA (ISO 14289). PDF/UA can be combined with PDF/A-3 so that a ZUGFeRD invoice can be accessible at the same time. Pure B2B invoices are not affected.
Clarify PDF/A requirements in your own SAP system
Do you need to deliver PDF/A — for e-billing, VDI 2770 documentation or archive — and don’t know what level your landscape requires? We check your ADS configuration and your document sources and tell you specifically where Level B is sufficient and where you need to go to the source.
