Error Prevention (Legal, Financial, Data)

Why it matters

Most of WCAG protects access to content. This one protects the outcome. A mistap that reopens an article costs nothing. A mistap that charges a card, signs a contract or empties an account costs something real, and it costs it permanently. W3C's reason for hanging that on disability is direct. People with reading disabilities transpose numbers and letters. People with motor disabilities hit keys they did not mean to hit. A safeguard is what turns an accidental input into an inconvenience instead of a loss.

Who this rule protects

People with motor disabilities make more accidental inputs, through no fault of their own, and a page with no safeguard turns each one into a consequence. People with reading disabilities transpose digits, which is how a quantity of 100 becomes 1000 and a travel date lands in the wrong month. Users with cognitive disabilities are likelier to commit to something before they have finished reading it. And everybody else has been saved by a review screen at least once.

How to check it yourself

1. 1Walk the checkout and see whether anything stands between the last click and the charge. A review screen, a stated cancellation window, or validation with a chance to fix things all count.
2. 2Try a destructive action such as deleting an account, a record or a saved address, and look for a confirmation that names both the action and its consequence, or a way to recover it afterwards.
3. 3Submit a test or an assessment if the site runs one, and check the candidate can review and change answers before the submission commits.
4. 4Read any cancellation promise closely. A window only counts if the page says how long it lasts and how to use it, and if cancelling means posting a letter, the page has to say so before the user submits.
5. 5Leave ordinary editing alone. This rule is about preventing mass loss, such as deleting a record, and it does not ask for a confirmation dialog on every save.

Failures we see most often

• One-click ordering with no review step, no cancellation path, and no validation the buyer can act on before the charge lands.
• Account deletion runs instantly from a single tap, with no confirmation and no recovery window.
• An e-signature flow moves straight to signing with no chance to read the final terms first.
• An online exam submits on the last answer, so a candidate who mistyped one has no way back into it.
• The page promises the order can be cancelled and never says how long the window is or where to go. A cancellation route the user cannot find is not a safeguard.

Who this one is for

Read from this rule's own note above, so the grouping and the note cannot disagree.

• Motor and keyboard-onlypeople who cannot use a mouse, or cannot use one precisely
• Cognitive and learningpeople for whom the difficulty is understanding, remembering, or staying with it

How to fix it

• Add a review step that lists the items, the price, the shipping address and the payment method, with an edit link beside each one.
• Ask for confirmation before anything destructive, and put the consequence inside the confirmation. Delete this invoice? It cannot be recovered. That does more work than Are you sure.
• Give deletions a recovery window instead of a dialog where you can, since an undo that lasts 30 days protects the user without interrupting anybody.
• Add a separate confirmation checkbox beside the submit button, unchecked when the page loads. It is the cheapest conforming safeguard there is, and it works because the user has to do two deliberate things rather than one.
• On a multi-step form, hold every step's data and let people move back through it, or show the lot on one summary before the final commit.

Passes vs. fails