Social media accessibility checklist for brand posts: alt text, captions and what the law requires

Add alt text to every image that carries information, publish accurate captions on every video with speech, and keep text on images readable. None of the EU, US or UK laws below names social posts; WCAG 2.2 is the standard to check against.

The nine main platforms offer different tools, and the laws cover specific organisations and services. Every platform and legal fact below was read on the platform's or the lawmaker's own pages on 2026-09-30.

Which platforms let you add alt text and captions?

"Not documented" means the platform's own help or developer pages we opened do not describe the feature. It does not mean the feature is absent.

Sources for the rows: Instagram help on alt text and reel captions and where they are available; Facebook help on alt text, Page video captions, profile video captions and .srt naming; LinkedIn help on alt text, auto captions and caption files; X help on image descriptions, .srt upload, accessibility features and video captions; TikTok's accessibility help; YouTube help on automatic captions, uploading caption files and supported formats; Pinterest help on alt text and closed captions; Threads alt text help; Bluesky's image and video post formats and its video announcement.

Three things follow from the table:

• Auto-captions are uneven. Pinterest's cannot be edited by the creator, and Instagram's are limited by location. Where you cannot correct the platform's captions, put accurate ones in the video itself.
• Caption files are the exception. Only Facebook, LinkedIn, X, YouTube and Bluesky document an upload, and Bluesky wants WebVTT. Keep an .srt and a .vtt of every brand video.
• Automatic alt text is a fallback. It describes objects, not the reason you posted the image.

Does the European Accessibility Act apply to social media posts?

The text does not say so. Directive (EU) 2019/882, the European Accessibility Act, applies to a closed list of services provided to consumers after 28 June 2025 (Article 2(2)): electronic communications services, access to audiovisual media services, parts of passenger transport services, consumer banking, e-books, and e-commerce services. Social media is not on the list.

The service most brands will meet is e-commerce: "services provided at a distance, through websites and mobile device-based services by electronic means and at the individual request of a consumer with a view to concluding a consumer contract" (Article 3). Annex I sets the accessibility requirements those websites and apps must meet. If you sell online to consumers in the EU, your shop is in scope. Whether a post that sends people to that shop is part of the service is not settled by the text. National transposition laws and regulators may say more.

Two limits matter for small brands:

• Microenterprises are exempt for services. A microenterprise employs fewer than 10 people and has an annual turnover or balance sheet total of no more than EUR 2 million (Article 3). Microenterprises providing services are exempt from the accessibility requirements (Article 4(5)).
• Third-party content is excluded. The Act does not apply to "third-party content that is neither funded, developed by, or under the control of" the business concerned (Article 2(4)(d)). Your own posts are under your control; comments from the public are not.

What about public-sector accounts?

Directive (EU) 2016/2102, the Web Accessibility Directive, covers the websites and mobile apps of public sector bodies. It applied to all their websites from 23 September 2020 and to their mobile apps from 23 June 2021 (Article 12). It excludes live time-based media, pre-recorded media published before 23 September 2020, and third-party content the body neither funds, develops nor controls (Article 1(4)). Its articles do not mention social media accounts.

What do US and UK law require?

The US Department of Justice's web accessibility guidance (18 March 2022) says businesses "can currently choose how they will ensure" their online services are accessible, and lists captions, text alternatives and colour contrast among the things to get right. Section508.gov sets out the federal agency duty. In the UK, section 29 applies the reasonable adjustments duty to service providers, and section 20(6) says that where the duty concerns information, reasonable steps include providing it in an accessible format.

Our reading: none of these sets a checklist for posts, but a business that takes bookings or customer questions on social media provides a service there. Posts that follow WCAG are the defensible position.

Which WCAG criteria apply to a social post?

WCAG 2.2 (W3C Recommendation, 12 December 2024) is written for web content, not for posts on someone else's platform. Five of its success criteria map onto what a brand controls:

A pre-publish checklist

Run it on every post. Items 1 to 4 cover the image and the video; 5 to 8 cover the post text.

1. Write alt text for the image's purpose. W3C's informative images tutorial says the alternative should convey the meaning shown, which "typically isn't a literal description." A product launch photo needs the product name and the detail you are selling, not "image of a box." Purely decorative images need none, per W3C's alt decision tree. Our advice: one or two sentences, and never start with "image of."
2. Put any text in the image into the alt text too. The decision tree says text that appears only in an image belongs in its alternative. A quote card's alt text is the quote and who said it.
3. Caption every video with speech, and check the captions. W3C's captions guide says automatically generated captions do not meet accessibility requirements "unless they are confirmed to be fully accurate," and that captions include non-speech audio needed to understand the content. Proofread names, numbers and negatives.
4. Choose burned-in or a caption file on purpose. W3C defines open captions as "always displayed and cannot be turned off," and closed captions as ones viewers can show or hide. Burned-in captions survive reposts and platforms with no caption upload, such as TikTok and Instagram, which document none. A caption file keeps the picture clean and lets viewers resize the text. Our advice: burn in where the platform has no upload, upload a file where it does.
5. Check contrast on text over images. 4.5:1 for normal text, 3:1 for large text, per WCAG 1.4.3. Busy photos fail most often; put the text on a solid band.
6. Write hashtags in CamelCase. The Scottish Government's social media accessibility standards (18 February 2025) list "camel case for hashtags": #SmallBusinessSaturday, not #smallbusinesssaturday.
7. Keep emoji few and out of the middle of sentences. The same standards ask for limited emoji use. Our advice: never use emoji as bullets or in place of words, and put them at the end.
8. Say where a link goes. WCAG 2.4.4 asks that the link's purpose be clear from the link or its context. Write "Book a table at our Leeds site:" before the URL, not "Click here."

Two more that are advice rather than rules: never put a date, price or deadline only in the image, and describe what happens in a video without speech in the post text.

For client accounts, add these items to the handover document in your client onboarding checklist. Accessibility sits alongside the other rules that apply to the same post: AI-content labels must also be clear and accessible under the EU AI Act, and a sponsored post still needs its #ad disclosure.

Frequently asked questions

Is alt text legally required on Instagram posts?

No law we read names Instagram or alt text on social posts. The European Accessibility Act covers listed services such as e-commerce, the ADA guidance does not address social media, and the UK Equality Act sets a general reasonable adjustments duty. WCAG 1.1.1 is the reference standard if a complaint arises.

Are auto-generated captions enough?

Not on their own. W3C says automatic captions do not meet accessibility requirements unless confirmed fully accurate. YouTube tells creators to review and edit its automatic captions, and TikTok and Facebook let you edit theirs, and LinkedIn lets you review them before viewers see them. Pinterest's cannot be edited by the creator.

Does the European Accessibility Act apply to my small business?

If you provide services and have fewer than 10 employees and no more than EUR 2 million in annual turnover or balance sheet total, you are a microenterprise and exempt for services. Above that, the Act applies if you provide a listed service, such as selling online to consumers in the EU.

How long should alt text be?

The platform limits are 1,000 characters on X, 500 on Pinterest and 300 per photo on TikTok. W3C's guidance for informative images is a brief description that conveys the meaning; put complex content such as chart data in the post text instead.

Should captions be burned into the video or uploaded as a file?

Burn them in where the platform has no documented caption upload, and when the video will be reposted elsewhere. Upload a file where the platform supports it, because closed captions can be turned off and on by viewers.

Sources

All read on 2026-09-30.

• Directive (EU) 2019/882 (European Accessibility Act), Articles 2, 3, 4 and Annex I. publications.europa.eu
• Directive (EU) 2016/2102 (Web Accessibility Directive), Articles 1 and 12. publications.europa.eu
• US Department of Justice, "Guidance on Web Accessibility and the ADA", 18 March 2022. ada.gov
• Section508.gov, "IT Accessibility Laws and Policies". section508.gov
• Equality Act 2010, sections 20 and 29. legislation.gov.uk
• W3C, Web Content Accessibility Guidelines (WCAG) 2.2, 12 December 2024. w3.org
• W3C WAI, Captions/Subtitles; Informative Images; An alt Decision Tree. w3.org
• Scottish Government, Social media accessibility standards, 18 February 2025. gov.scot
• Platform help and developer pages: Instagram, Facebook, LinkedIn, X, TikTok, YouTube, Pinterest, Threads and Bluesky, as linked under the platform table.