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As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = {UA-2,A-4F} ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader. You also need to remove the A-4F.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-2, and I think it's A-4F except for media9. I've gotten a 400 page Linear Algebra book to be UA-2. So it's definitely doable, and things are getting better day by day.

As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = UA-2 ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key and specify pdfversion=1.7).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-2 as well as a 400 page Linear Algebra book. So it's definitely doable, and things are getting better day by day.

As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = {UA-2,A-4F} ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-2, and I think it's A-4F except for media9. I've gotten a 400 page Linear Algebra book to be UA-2. So it's definitely doable, and things are getting better day by day.

As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = {UA-2,A-4F} ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader. You also need to remove the A-4F.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-2, and I think it's A-4F except for media9. I've gotten a 400 page Linear Algebra book to be UA-2. So it's definitely doable, and things are getting better day by day.

As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = {UA-2,A-4F} ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-1, and I think it's UA-2 except for media9. I've gotten a 400 page Linear Algebra book to be UA-2. So it's definitely doable, and things are getting better day by day.

As David Carlisle said, this is under active development, so much of it is in a great amount of flux. But there are some guidelines I can share.

1. As a consequence of "active development", make sure everything is updated: you definitely need 2025, and then How do I update my TeX distribution?. Make sure you're using LuaLaTeX.
2. I think the current first command is now at

\DocumentMetadata{ pdfstandard = {UA-2,A-4F} ,tagging = on ,lang = en ,tagging-setup={math/setup=mathml-SE}} } 

3. If your document must be approved by Blackboard Ally, then tagging-setup currently also needs the key math/alt/use. Unfortunately, this makes your document less accessible in Adobe Reader.
4. The LaTeX team has been using VeraPDF to verify pdfs. It has a command line tool that is quite useful. I've also found PDFix useful - it's not quite a comprehensive as VeraPDF, but it has a better GUI to locate problems. There's also PAC, but it's Windows only, has a bug regarding tabular, and can only handle up to UA-1 (which means you need to remove the math/setup key).
5. https://latex3.github.io/tagging-project/tagging-status/full shows the known tagging status of packages and classes. Do not use anything labeled "no support". If you can switch to "compatible", do so. If you have something under the other categories, see what VeraPDF says. You can also check on the issues for a particular package or class and see if someone helpful has already solved your problem.
6. texdoc tagpdf will provide some help. See also https://latex3.github.io/tagging-project/documentation/prototype-usage-instructions.html. Your images will need alt text, and your tables will need to specify their headers.

I've gotten a 1000 page Calculus book to be UA-2, and I think it's A-4F except for media9. I've gotten a 400 page Linear Algebra book to be UA-2. So it's definitely doable, and things are getting better day by day.