Explainer

How Long Should an NDA Last? UK Durations Explained

There's no fixed legal term for a UK NDA. Here's how to set a duration that's enforceable — typical terms by situation, why indefinite gags get challenged, and how trade-secret survival works.

By Richard Wood, Founder6 min readUpdated 31 May 2026Last reviewed 31 May 2026UK lawenforceabilityNDA basics

"How long should it last?" is the question that trips people up most when setting up an NDA. Too short and you lose protection while the information is still sensitive; too long and a court may not enforce it. Here is how to get it right.

This is general information, not legal advice

NDASafe is a document preparation service, not a law firm. Our templates are legally reviewed against applicable UK law at the point of release, but every situation is different. Where significant value, unusual risk or a cross-border element is involved, take independent legal advice before you sign.

Typical durations by situation

SituationTypical term
General commercial discussions2–3 years
Business sale / M&A2–3 years (process); longer for trade secrets
Employee / contractor confidentialityDuration of engagement + a reasonable tail
Trade secrets (source code, formulae)Indefinite, while they remain secret

Why indefinite gags get challenged

UK courts test confidentiality terms for reasonableness. An indefinite, blanket obligation over ordinary business information looks like an unreasonable restraint and is the kind of clause a court will read down or refuse to enforce — see are NDAs enforceable. The fix is to separate ordinary information (fixed term) from defined trade secrets (indefinite survival).

Set the term to the information

Ask how long the information actually stays valuable if kept secret, and set the term to that. A product launching in six months needs protection for the run-up, not for a decade.

Sensible terms, built in

NDASafe templates use reasonable default durations with indefinite trade-secret survival, and let you set your own term. £29 each, £79 for all eight.

Frequently asked questions

How long should an NDA last in the UK?

There is no fixed legal term. Two to five years is typical for ordinary commercial information, with 24 months a sensible default. Genuine trade secrets can be protected indefinitely because they only stay valuable while they stay secret.

Can an NDA last forever?

A perpetual obligation can be reasonable for true trade secrets, but an indefinite blanket gag over ordinary business information is likely to be challenged as unreasonable. The safer approach is a fixed term for general information plus indefinite survival for defined trade secrets.

What happens when an NDA expires?

The confidentiality obligation ends for the information it covered, except for anything expressly stated to survive (typically trade secrets). The parties are then free of the duty unless another agreement continues it.

Templates mentioned in this guide