An NDT certificate has two clocks running at once and they expire independently. The certification cycle is normally five years from the date of certification, after which the technician must be recertified. The vision examination is annual, and a lapsed eye test invalidates the certification just as effectively as a lapsed cycle — a technician whose near-vision check ran out last month is not qualified today, whatever the certificate says.

The near-vision requirement is Jaeger Number 1 or equivalent type at a distance of not less than 300 mm, in at least one eye, natural or corrected. The two schemes state that distance slightly differently — SNT-TC-1A says not less than 12 in (30.5 cm) and ISO 9712 says not less than 30 cm — so test at 305 mm and both are satisfied. Equivalents in normal use are Times Roman N-4.5 and the Ortho-Rater. Corrected vision counts, which is why the test has to be repeated annually rather than once at certification: prescriptions drift. A separate colour-contrast check is required where the method depends on discriminating colour or shades of grey — penetrant dye, magnetic particle contrast, radiographic film densities — at the interval set by the written practice or certification body.

Recertification is not automatic. Under an employer scheme it may be by examination or by documented evidence of continuing satisfactory performance, as the written practice allows. Under ISO 9712 the certificate is renewed at five years on evidence of a current vision test and continuous work without significant interruption, and at ten years recertification additionally needs a practical examination or acceptance under a structured credit system. Either way the paperwork takes time, so most employers open a window several months before expiry and start the process then.

An interruption in service — long-term sickness, a spell in a non-NDT role, redundancy — is treated separately from expiry. Most written practices require re-examination after an extended break from the method, and time out of the method does not extend the five-year cycle. Work performed after expiry is not covered by the certification, and reports signed in that period are open to challenge.

Worked example

Year certified	2022
Month certified (1–12)	3
Certification cycle	5
Current year	2026
Current month (1–12)	8
Year of last near-vision test	2026
Month of last near-vision test (1–12)	2
Vision test interval	12
Recertification window	6
Expiry year	2027
Expiry month (1–12)	3
Months to expiry	7
Months until the recertification window opens	1
Months until the next vision test	6
Certification in date	1

Certified March 2022, index 2022×12 + 2 = 24266. Five-year cycle adds 60 months: 24326, which is 2027×12 + 2, i.e. March 2027. Today is August 2026, index 2026×12 + 7 = 24319, so 24326 − 24319 = 7 months to expiry and the six-month window opens in 1 month. Last vision test February 2026, index 24313: six months elapsed, so the annual test is due in 12 − 6 = 6 months.

Use at your own risk — verify before you act

These calculators support, and never replace, the judgement of qualified NDT and engineering personnel. Results are provided as is, without warranty of any kind, express or implied, and must be independently verified against the governing code edition named in your contract before being used in any inspection, acceptance, rejection, radiation-safety or fitness-for-service decision. By using them you accept full responsibility for how the results are applied; NDT Inspect, its owners and contributors accept no liability for any loss, damage, injury or death arising from their use or from reliance on them. If a result matters to safety, check it by hand and have it reviewed by a competent person.