Subtitles vs closed captions

Four terms cover almost every case. Two questions separate them. Does the text include sound and speaker information, or only dialogue? Can the viewer turn the text off?

Subtitles

Subtitles show the dialogue as text. The usual reason is language: the viewer can hear the audio but does not understand it, so the subtitles give a translation. W3C uses “subtitles” for spoken audio translated into another language. MDN says the same: subtitles are for viewers who have sound but cannot understand it.

Closed captions

Closed captions show the dialogue and the other sounds that a viewer needs: who is speaking, sound effects, and music. They are made for viewers who cannot hear the audio, or cannot hear it well. “Closed” means the viewer can turn them on and off. W3C says most captions are closed.

Open captions

Open captions have the same content as closed captions. The text is part of the picture, so it is always on and the viewer cannot turn it off. Editors “burn in” open captions when they export the video.

SDH

SDH means subtitles for the deaf and hard of hearing. An SDH file is a subtitle file that also carries the caption content: speaker names, sound effects, and music. Netflix, for example, treats SDH as its own file type, next to normal subtitles, and marks titles that have it with an SDH badge.

To write SDH, read the SDH guidelines. This guide does not cover the writing rules.

The same text has different names in different places. The law in each region shows this.

• US: US law and US TV say “closed captioning”. The word “subtitles” usually means a translation.
• UK: UK law says “subtitling” for the access service that helps deaf and hard of hearing viewers. A UK broadcaster's “subtitles” are often what a US broadcaster calls captions.
• EU: EU law says “subtitles for the deaf and hard of hearing”, which is the same idea as SDH.

W3C says “captions” and “subtitles” can mean the same thing in different regions. It also notes that some regions use “subtitles” for same-language text.

When you take an order, do not trust the word alone. Ask two things. What language is the text? Does it include sounds and speaker names?

HTML video marks the difference in code. A <track> element has a kind of subtitles or captions.

Each law below has a narrow scope. The table states it. The sections after the table give the detail.

TV captions: 47 CFR 79.1

The FCC adopted its TV caption rules in 1997. The duties phased in over the following years. The rules carry out section 713 of the Communications Act and are now in 47 CFR 79.1.

• Who: video programming distributors (TV stations, cable and satellite providers) and the programmers that supply them.
• How much: captions for 100% of new, nonexempt English and Spanish programming. The count is per channel, per calendar quarter. Older programming needs captions for 75%. The rule treats programming first shown on or after 1998.01.01 (analog) or 2002.07.01 (digital) as new.
• Exemptions: for example, programs sent between 2 a.m. and 6 a.m. local time, programs of mostly non-vocal music, and channels with less than $3,000,000 in gross revenue in the last year. A small channel must still pass captions through.
• Quality: captions must be accurate, in sync, complete, and placed so they do not block key parts of the picture.

Internet video: the CVAA

The Twenty-First Century Communications and Video Accessibility Act of 2010 (CVAA) is Public Law 111-260. It became law on 2010.10.08. Section 202 told the FCC to require captions on internet video. The FCC rule is 47 CFR 79.4.

The rule covers video that was shown on US TV with captions. It does not cover consumer-generated media. Video made only for the internet is outside it. Deadlines came in steps:

• Full-length programs, prerecorded and not edited for the internet: 2012.09.30.
• Full-length live and near-live programs: 2013.03.30.
• Full-length programs edited for the internet: 2013.09.30.
• Clips: 2016.01.01 for a single excerpt, 2017.01.01 for several excerpts in one file, and 2017.07.01 for live and near-live clips.

Section 203 of the CVAA covers devices. Where technically feasible, a device with a picture screen that shows video with sound must decode captions. Screens under 13 inches need this only if it is achievable. Recording devices must pass captions through, where achievable, so a viewer can turn them on or off during playback.

The ADA

The ADA has two parts that touch captions. Neither one sets a percentage.

• Title III, public accommodations. 28 CFR 36.303 says a public accommodation must take the steps needed so that people with disabilities are not excluded for lack of auxiliary aids and services. The list of examples includes open and closed captioning, and real-time captioning. The duty ends where an aid would fundamentally change the service or cause an undue burden.
• Title II, state and local governments. A DOJ rule published on 2024.04.24 requires their web content and mobile apps to meet WCAG 2.1 Level AA, with some exceptions. That level asks for captions on prerecorded audio (criterion 1.2.2) and live audio (criterion 1.2.4) in synchronized media. An interim final rule of 2026.04.20 moved the deadlines. A government with 50,000 people or more has until 2027.04.26. A smaller government or a special district has until 2028.04.26.

TV services

Section 303 of the Communications Act 2003 tells Ofcom to write a code that helps people with disabilities enjoy programmes. The code covers subtitling, audio description, and sign language. Ofcom publishes it as the Code on Television Access Services.

Section 303 has been in force since 2003.12.29. It applies to S4C Digital, licensed public service channels, digital TV programme services, TV licensable content services, and restricted TV services. The Act sets targets. A service measures them as an average over 12 months, across programmes that Ofcom's code does not exclude. Advertisements are not programmes.

Ofcom's code can set interim targets and the details. Read the current code before you plan a delivery for UK TV.

On-demand services

The Media Act 2024 changed the rules for on-demand services and added a regime for the largest ones, called Tier 1. Sections 37 to 40 of the Act came into force on 2024.08.23.

In 2026, Ofcom asked for comments on a draft Tier 1 Accessibility Code. The draft sets targets for subtitles, audio description, and signing that rise in steps. From the fourth anniversary of a service's relevant date the targets are 80% subtitles (90% for BBC iPlayer), 10% audio description, and 5% signing. Comments closed on 2026.08.07. Ofcom expects to publish the final code later in 2026. Until then the code is a draft, so check Ofcom's site.

Two EU laws apply. They split the work: one covers the programmes, the other covers the services that deliver them.

The programmes: AVMSD article 7

The Audiovisual Media Services Directive, as changed by Directive (EU) 2018/1808, asks each Member State to make sure that media services become “continuously and progressively” more accessible. The Member State uses proportionate measures. Providers report to their national regulator on a regular basis. The article sets no percentages. National law decides the detail.

The delivery: the European Accessibility Act

Directive (EU) 2019/882 is the European Accessibility Act. Member States had to publish national laws by 2022.06.28. They apply the measures from 2025.06.28, to services provided to consumers after that date.

One covered service type is “services providing access to audiovisual media services”. Think of websites, apps, media players, connected TV services, and electronic programme guides. Annex I asks these services to:

• make electronic programme guides usable and show which programmes have access services;
• send access services in full and with adequate quality: subtitles for the deaf and hard of hearing, audio description, spoken subtitles, and sign language interpretation;
• keep them in sync with sound and video;
• let the user control how they show and use them.

The Act does not say how much of a catalog needs subtitles. Its recital 31 sends the accessibility of the media services to the AVMSD. Microenterprises that provide services are exempt (article 4(5)).

Start with the buyer's delivery specification. When there is none, use this table. The law decides some cases. Your audience decides the rest.

When one video needs both a translation and an accessibility track, make two files. Keep the sound and speaker information in the original-language file and translate the dialogue for the rest.