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Understanding the Limits of Microsoft’s Accessibility Checker

Jun 30, 2023

Microsoft 365 is essential productivity software for 1.3 million U.S. businesses. Given that 1 in 4 U.S. adults has a disability — and that employment among people with disabilities has been rising sharply since 2020 — many of these businesses probably employ people with disabilities. How can they be sure their Microsoft 365 documents are accessible to workers with vision impairments, hearing loss, learning disabilities, and other sensory or motor differences?  

Microsoft’s built-in Accessibility Checker tool is a good place to start, but all automated accessibility tests have limitations. With that in mind, here are a few important things the Microsoft Accessibility Checker can (and cannot) do.  

Related: Do Microsoft Word Docs Need to Be Accessible? 

3 Limitations of the Microsoft Accessibility Checker

The Microsoft Accessibility Checker is a helpful, thoughtfully designed feature, but it isn’t perfect. As you run the Accessibility Checker, be aware of the following issues:  


1. The Accessibility Checker isn’t available on all Microsoft 365 apps or operating systems. 

Accessibility Checker is available in all web-based Microsoft 365 apps, which include: 

  • Outlook (email)
  • Word (documents)
  • Excel (spreadsheets)
  • PowerPoint (presentation slides)   
  • OneNote (notes)
  • Sway (newsletters and other designed documents)
  • Visio (diagrams) 

On a Windows machine, all 365 apps include the Accessibility Checker with the exception of Sway. The same is true for 365 on a Mac, although this version also leaves out Visio. But mobile platforms — iOS and Android — don’t support the Accessibility Checker. 

Find the full list of 365 apps and platforms that include the Accessibility Checker here.


2. The Accessibility Checker won’t recognize missing alt text on tables. 

All images — including tables and graphs — need a text description. That’s the only way people who use screen readers will get the information embedded in your image. 

The Accessibility Checker does identify missing alternative text (alt text) in most non-text content. It can even suggest original alt text using artificial intelligence. But, for whatever reason, this tool won’t identify missing alt text in a table. You’ll need to check tables for alt text manually. 

Related: 5 Steps for Writing Alt Text for Accessibility 


3. The Accessibility Checker may misidentify harmless elements as accessibility issues.  

Automated accessibility tools are prone to false positives, and Microsoft’s Accessibility Checker is no different. These mistaken red flags are side-effects of scanning for things that are usually — but not always — accessibility problems.    

For example, this tool looks at a document’s use of color to spot barriers like poor contrast and the use of color alone to convey information. If color is the only way you express something — using a red font to convey negative numbers in Excel, for instance — people who don’t distinguish colors well miss out on important information.

But not all use of color conveys information. Color can safely be used for design elements, as long as it doesn’t create contrast issues. Microsoft’s Accessibility Checker might flag such a design object as an objectionable use of color even when it isn’t. 

The Accessibility Checker might also tell you you’re missing closed captions in a video. But if your video doesn’t have any dialogue, there’s nothing to caption. Microsoft’s accessibility tool also won’t recognize burned-in or in-band captions in time-based content.  

Related: How Do “Burned In” Captions Affect Accessibility?   

Adding Manual Review Alongside the Accessibility Checker

For all these limits, the 365 Accessibility Checker is a great first-line tool for removing barriers from digital workplace content. It spots common accessibility issues like: 

  • Simple table structures, which assist in keyboard navigation.
  • High color contrast ratios for text, necessary for many people with low vision.
  • Document access restrictions, which won’t work with screen readers.
  • Logical order in slide objects, for better presentation through assistive technology (AT).
  • Organized document headings, for simpler scanning with or without AT.

After you verify and fix everything the Accessibility Checker flags, check your documents manually. You’ll spot what digital tools can’t. If you’re not sure what to look for, review the principles of the Web Content Accessibility Guidelines (WCAG). 

Microsoft’s Accessibility Checker can help you create business documents that are more accessible — and easier to understand — for the whole workforce. But without detailed human review, barriers are likely to remain. 

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