Data
How long do NDAs last?
How long do NDA obligations last?
In the ContractNLI dataset, 422 of 607 NDAs say some obligations continue after the agreement ends. Where that clause names a fixed period, the median is 3 years; 61 of the 422 make the duty open-ended.
- 160 name a fixed period (37.9%)
- 61 make it open-ended — for as long as the information stays secret, or indefinitely (14.5%)
- 201 say obligations survive but give no period in that clause (47.6%)
Period named in the clause
| Period named in the clause | NDAs |
|---|---|
| 1 year | 10 |
| 1.5 years | 6 |
| 2 years | 31 |
| 3 years | 48 |
| 4 years | 1 |
| 5 years | 54 |
| 7 years | 3 |
| 10 years | 5 |
| 12 years | 1 |
| 20 years | 1 |
Before you sign
Look for the survival or term clause and check three things: how long the duty lasts, when that period starts counting, and whether trade secrets are carved out for longer. Open-ended wording is common here too, so it is worth asking whether a plain end date would work for both sides.
How we counted
ContractNLI (Koreeda & Manning, Findings of EMNLP 2021; CC BY 4.0) labels 607 NDAs for 17 statements, including whether obligations survive the end of the agreement, and marks the sentences that support each label. For the NDAs labelled “survive”, we searched only those marked sentences for a period in years or months, or for open-ended wording. Where several periods appeared, we took the longest. Periods run from different starting points — signing, disclosure, or the end of the agreement.
Limits
- Pattern matching on text: some periods may be missed or misread. We publish the rule we used, and we checked a sample of 50 by hand.
- “No period given” means none appeared in the marked sentences — the NDA may state a term elsewhere.
- About 32 of these documents are unfilled templates (for example “[insert number] years”).
- Trade secrets are often protected for longer than other information; a single number hides that.
- 607 NDAs collected for research from SEC filings and web search — not a sample of every NDA.
Source: ContractNLI, Koreeda & Manning (2021), CC BY 4.0. The duration counts are ours.