JohannaH

I want to add some information here. PAC is (much) more strict than necessary. PAC2024 is even worse than PAC2021 when it comes to unnecessary failures and warnings that don't add anything to accessibility (WCAG) in my opinion.
According to European law only WCAG rules should be applied to digital documents like PDF (clause 10 of the EN301549). PDF/UA is an official standard for PDF, but it's not required in the EN301549 (EU) or section 508 (US).
Something like the "alternative description" on a Link-tag that PAC and PDF/UA require is not needed for WCAG or for accessibility. In fact, if screen readers would be able read that attribute it would probably cause extra problems. It would either replace the link text or add something to it. Better to have just a good link text.
The "missing Bounding Box" attribute isn't part of PDF/UA (ISO 1.7) or WCAG as far as I know. I have found some comments on bounding boxes in general in that ISO. And I found also that extra attention must be paid to bounding boxes of tables and figures, but it wasn't clear to me if that extra attention is part of the PDF reader (like Acrobat) or the PDF creator. It's not in the Matterhorn either (list of failures in PDF/UA). Anyway, I couldn't find anything that would explain why PAC treats a missing Bounding Box attribute on a tag as a failure. The only failure I have encountered in my work as an auditor and remediator of PDFs is when a Figure tag points to the wrong part of the visible page. That can be fixed by putting the Bounding Box attribute on that tag and to make sure it points to the right section of the visible page. But that seems to be a rare problem.
I do agree with what Layoutman said about the other problems like placement (block or inline) of objects and the many problems caused by InDesign with span tags and story tags. It would be wonderful if Affinity Publisher could do a better job.

I make accessible PDFs, because my best customers cannot any more accept anything else. The situation has been here the same over 2 years. That's declared by the rules how public money can be consumed. 
Adobe Indesign offers a way to make PDFs which Adobe call "Accessible". Hopefully Serif succeeds to avoid copying the inferior solution of Adobe. Let me explain some of the most idiotic features of the Adobe solution:
The result is not Accessible - no matter what Adobe Acrobat accessibility checker happens to write. Actually Adobe has understood how to avoid lawsuits. Acrobat doesn't claim anything accessible. It says only "No errors were found". As useful as a blind chicken!
The result does not fulfill formal PDF/UA nor WGAC accessibility criterions. A good formal accessibility tester is PAC 2021. Virtually any image, link, table ad form field is tagged wrong by Indesign and must be manually fixed in Acrobat. Especially often attribute objects bounding box and placement  are missing or wrong. Unfortunately fixing manually is not so easy. There are at least as many errors as there's images, links tables and form fields. In addition the the tag tree is full of Span and Story tags. The tags which need fixing are hidden deep.  It's much easier to tag say 100 page book manually in Acrobat than to fix the mess generated by Indesign.
A big part of the problem is Adobe's idea to use text styles as the basis of tagging. Layout artists hate it. (I like use a couple of them because their artistic ability and stylistic confidence is a high boost of what I can deliver).
In Indesign any piece of text must in any case to be selected  in Indesign and marked to be included to the tagged content. It would be a gift from the heaven if  the used tag could be inserted in this phase and the tagging by text style could be totally skipped. If someone really wants the story and span tag -jumble caused by tagging by text style -idea I gladly like to let him continue in his masochism, but I do not want the same. That's way I tag manually in Acrobat. 
Tagging in Acrobat has a drawback. The customers often want to make content changes. They do not understand why in the hell I do not give already the first version as an accessible PDF, but before making the tagged PDF I require an email confirmation "this version is final and the next change will be paid separately"
The customers have learned to require some quality. Many of my rivals are dropped because
- some of them only said "this PDF is accessible" I reality there could be say 100 red and 200 yellow errors in PAC2021 checklists and the screen reader simulation could be unreadable.
- some of them did not lie, but they do not know how to convert PDFs accessible in Acrobat or have found it too difficult.
Today the customers do not accept a single red nor yellow error in PAC2021's PDF/UA nor WGAC checklists. In addition the PAC2021's screen reader simulator must show a simple linear layout which contains proper captions and alt texts for images and links. The text level must not change randomly. A single paragraph must look a single paragraph.
Adobe stuff costs too much. Your products are more affordable and the developments in ver.2 make also professional usage meaningful. Hopefully this happens also in the field of accessibility. But do it properly, without copying the Indesign approach.
 

I'm going to test this.

Lo and behold! See what has been added to Affinity version 2.3. Alt text (for screen reader accessibility) can now be added to images and objects in a PDF file. Looks like we have to wait longer for ePUB export.
https://affinity.serif.com/en-us/whats-new/
Tags Panel for adding alt text to images and objects
The new Tags Panel in Affinity Publisher allows you to add alt text to any image or object when exported to PDF for accessibility purposes. To use, just open the Tags Panel from the Window menu, select the image or object you want to add alt text to, and add your description in the box.
Alt Text Source
As well as adding your own custom description to any object, you can also choose to scrape the alt text from the Title, Description or Headline meta data which may be embedded within the image in question.
Mark as Decoration
You also have the option to ‘Mark as Decoration’. This means no image description will be exported or used by screen readers as the item is purely there for decorative purposes rather than important to the understanding of the document. Marking as a decoration is primarily used to positively tag an image as not needing a description, so it’s not flagged in preflight.
Preflight
Options have also been added in preflight to make it easy to check your document for any missing alt text should you wish. When creating or editing a profile, you will see a new section for alt text. Here you can choose whether you want preflight to return a warning if images, placed documents or vector objects do not have alt text added (or marked as decoration).
Export
There is now a new ‘Tagged PDF’ option in the advanced section of PDF export. This is required to be checked if you wish to export your PDF, including any tags you have added.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I found a free online tool (PAVE) to get your PDFs tagged. It's not perfect, although they really tried to create a good product. But at least you get most tags in your pdf without the extra costs of using Acrobat DC Pro.
You could use the free PDF XChange Editor to adjust the tags. I'm still not sure if you can make all the changes with XChange like with Acrobat. It can't tag the whole document at once, but I think you can put them in one by one. Windows only.
Check the whole thing with PAC. That's the best tool for automated checking and also for checking the reading order (=tag order), the texts, the use of the right semantic tags (screen reader preview button) and so on. It's for Windows only.
These three tools won't solve the problem but at least it's something.
 
https://pave-pdf.org
https://www.tracker-software.com/product/pdf-xchange-editor
https://www.access-for-all.ch/ch/pdf-werkstatt.html
 
I hope Affinity Publisher will be able to create proper tags in one of the next versions. Without that the app will become useless for most users in the coming years because of changing laws. Within a few years most countries won't allow inaccessible PDFs on commercial websites anymore. Many governments (US, UK, EU) aren't allowed to use inaccessible PDFs already.
I like the Affinity products, so please solve this problem, Serif!!

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

@erssie, you could try the Pave website to change the PDF that Affinity produces into an accessible one. 
https://pave-pdf.org/?lang=en
They offer a free online tool which might be the best option for you.
Accessible PDF's is more than just the alt-texts. You'll need tags so a screenreader can easily read the text. If there are any headings, lists or tables in it the tags will show that to the screenreader, just like on a website. Even if your blind group members tell you it's fine without them it still might cause a problem when someone uses a different PDF reader. Pave should be able to fix that for you.
To check the PDF when it's finished the also free PAC tool might help. It's what most people working in accessibility use to check PDFs.
https://pdfua.foundation/en/pdf-accessibility-checker-pac/register
This tool is simple to use, but make sure you read the manual to understand the outcome. Just ask here if you have questions and I'll try to help, because I don't think you'll need to fix everything that PAC shows as a fault. It's a bit too strict.

I totally agree with others on this subject. It's part of my job to check accessibility of PDFs. And most of them aren't accessible.
But according to the law all content on a government (related) website in my country (part of the EU) and many other countries should be accessible. So that includes all PDFs on that website. Of course there is an exception for old documents. But new PDFs just have to be properly tagged so a screenreader is able to use it and read it to a blind person. And when that's the case, then it is usually also accessible to other tools used to help people to read or understand digital content.
Within a bit more than a year the process of making all content on all websites in the EU will start and in June 2025 all company websites have to be accessible except the ones from very small companies. https://en.wikipedia.org/wiki/European_Accessibility_Act
If Affinity doesn't solve this problem it will be impossible for designers to use this software as their products can not be published on websites anymore. We would be left with Adobe products just because they do have tags in PDFs, not because they are very good at it, they are not.
I love all Affinity software, but I have to use other software to create accessible PDFs, like Adobe Acrobat, MS Word, Axes4 (Word Plugin and PDF QuickFix). I want to use Affinity!!
Affinity team, please add tagging to creating PDFs!
And please have a look at other things like a contrast checker, a checker of the the headings, and so on.
Here you'll find some info:
https://www.pdfa.org/wp-content/uploads/2019/06/TaggedPDFBestPracticeGuideSyntax.pdf
https://www.pdfa.org/wp-content/uploads/2014/06/MatterhornProtocol_1-02.pdf
https://www.axes4.com/resources.html
https://www.access-for-all.ch/en/pdf-accessibility-checker.html
https://www.access-for-all.ch/en/pdf-accessibility-checker/vip-pdf-reader.html

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I tend to support the small guys, knowing they don't offer everything the big guns do. But the big ones are the abusive ones, and Serif has thus far pleased me no end - feature- and price-wise. I'm happy to be Adobe-free, and I'm looking forward to more great Affinity features, while respecting the disappointment of those who expected more. For them there's always Adobe. 
In terms of money, my financial support of Serif is a given, for obvious reasons. I'm grateful Affinity exists, and offers what it does. Here's to more!

Look, with the v2 launch coming in hot and people all upset that 40% off isn't enough, I hate to pile on during what is Serif's worst day in years... but it's time for real talk about a problem that makes the Affinity suite literally unusable. We have to tackle problems head on to move forward and I think we're all mature enough here to have an uncomfortable discussion. Well, some of us are. 

What is this dangler called, and why is it there?
It haunts me.

I am also shocked. ePub export was the first thing I looked for when I saw the Affinity 2 announcement. Serif, please give us your roadmap for this very important feature that needs to be part of Affinity Publisher.

For formatting books, I moved away from Publisher to Word so I can export epubs quickly and not have to format the book twice.

I checked the specs of this new version of Publisher. There are many nice features in there. What seems to be missing is the export of a tagged and accessible PDF (PDF/UA). Also I don't see how I could publish a digital book (EPUB3) with this app.
I really hoped for some competition for Adobe InDesign which is capable of such output. Even Word produces such accessible PDFs and EPUB (with WordToEpub plugin).
With the output of Publisher still focused on print only I don't have many reasons to use it. All digital documents for governmental institutions and, within a few years in the EU, for many commercial companies as well, need to be accessible. Besides, I don't want to exclude anyone from using my documents.
I don't mind if I need to do some extra work with a tool like Adobe Acrobat for PDF or Sigil, Calibre, Ace by Daisy for EPUB3, but now I need Word, InDesign or some other app to create the document or book when I really would have liked to use Affinity Publisher.

I'm trying not to be shocked that they haven't included ePub and other export options in the new version. A quick search shows it being asked for in 2018 so maybe it's never going to happen. Disappointed but no need to upgrade so...

I'd love to see this worked on as well. I know it's not a very sexy feature but it's such important functionality!

I agree with JohannaH. Accessible PDF output is essential to many of my clients, and I was so hoping that we would get tagged PDF export with this version. I don't fancy hand remediating 150-page reports from scratch for accessibility and I cannot afford to outsource remediation. So, back to InDesign for those types of documents.

The tags and reading order would be created when the PDF is exported from the source design/layout program.
We "assign" tags in the layout, but they don't actually get created until the PDF is being exported.
Affinity already knows how to make a PDF because any software that creates any kind of PDF must follow the international standards for PDFs called ISO 32000. Any PDF must be made to the standard so that the PDF file can be read or viewed by any brand of PDF reader. This is very common in the manufacturing and software world. It's crucial in printing as we see with out PDF/X requirements (another international standard from the ISO for press-quality PDFs).
All Affinity has to do now is add the standards for PDF/UA ISO 14329, an extended version of the PDF standards that includes the requirements for accessibility in a PDF, such as tags and reading orders.
They've already built their programming engine to create general PDFs, now add in the accessibility requirements. I won't be rude and say it's easy for Affinity to do that, but it's not that complicated, either. The hardest part is making the fricking PDF itself to begin with, and they've already done that.
@sheriffderek, since you already know HTML and CSS, let me make a comparison that could help put this into perspective.
HTML requires that standard tags be used to encase all parts of the content, like <p>, <h1>, <h2>, etc.  You can't publish a webpage without having your content tagged.
Desktop publishing, on the other hand, has traditionally NOT required this type of tagging, unless you were specifically doing XML, SGML, or tagged content publishing. Tags and accessibility are relatively new to the graphic design industry.
In websites, CSS is what's used to style the content, instructing a browser to take all <p> content and use Source Sans font, for example. Or take all <h1> content and color it RBG ## ## ##. Web developers design with CSS.
CSS is directly like what we do now with our Affinity Publisher paragraph and character styles: we define how a particular portion of text will look, its font, color, alignment, size, etc. — just like CSS does in HTML.
At this point, Publisher doesn't let us designate what tag to put on each type of text. Styles are the most convenient way to do this, as Adobe InDesign has shown for the past decade. As a graphic designer, I need to make a style for my subheadings that specifies Roboto Bold, 24 pt on 26 pt leading, left aligned, no hyphenation — and also tag it as <h2> when the PDF is exported.
We don't put tags inside the desktop publishing layout— no accessibility tags are in the layout. Instead, we give the instructions to add the tags when the PDF is exported. (Note, this is NOT XML, which does tag the content in the layout. PDF Accessibility tags are not XML tags.)
So Affinity needs to expand their current PDF-export utility to include accessibility tags and reading order, and then give us a way to assign the tags and control the reading order in our layouts.
And as a bonus, they could port that utility over to Designer, giving us the ability to make accessible info graphics and small projects in that program, too.
If Affinity did that, eat your heart out Adobe!  😁  Illustrator doesn't have a shred of accessibility in it.
Imagine if we designers had both layout and graphics programs that could make accessible PDFs.
Wow. Game changer for the industry.
 
—Bevi Chagnon / PubCom.com
Designer | Teacher | Author | Expert for Accessible Documents
Learn about accessibility at our free blog, www.PubCom.com/blog
US Delegate to the ISO committee for the PDF/UA standards.
Advisor and beta tester to software companies for building accessibility tools.
 

Adding my support as another customer who is looking for this functionality.

I love Publisher but the documents are virtually useless to me unless I can create them as accessibility tagged pdfs.  Is there any movement on doing this? It seems as this should be an urgent and pressing concern.