How Long Is an IQ Test Valid? When an IQ Score Goes Out of Date

An IQ test result has no built-in expiry date, but most places that rely on one set their own limit. US special-education law requires a child’s re-evaluation, which need not include an IQ test, at least once every three years unless the parent and the school agree it is unnecessary. The Social Security Administration treats a child’s IQ score as current for one to four years, depending on age and score, while a score from age 16 onwards can stay current indefinitely if it still fits how the person functions. The limits exist for practical reasons: scores shift a little by chance, children change, and the norms a test is scored against grow old. This guide explains what “valid” means for a test, how long institutions accept a score, how stable scores are over the years and when a retest is worth it.

• Short answer: an IQ score does not expire. A school, agency or court decides how recent it must be.
• US special education: re-evaluation at least every 3 years unless the parent and school agree it is unnecessary, and no more than once a year unless both agree (34 CFR 300.303).
• Social Security (children): a score is current for 1 to 4 years depending on age at testing and on whether the IQ is below 40; from age 16 it can be current indefinitely (DI 24583.060).
• Stability: adult rank order is stable at about .76 across five years, not perfect (Breit and colleagues, 2024).
• Practice: retaking the same test raises scores by about .26 standard deviations, roughly 4 points (Hausknecht and colleagues, 2007).
• Old norms: raw scores rose about 0.28 points a year, so a score on norms ten years old reads about 3 points kinder than on fresh ones (Pietschnig and Voracek, 2015).

Does an IQ test result expire?

Not on its own. An IQ score is a record of how someone performed on one occasion against one norm sample, and a record does not go off. What changes as time passes is how much weight a reader should put on it. The word “valid” hides three different questions, and older advice often blurs them, so it helps to separate them.

A test with good validity and reliability does not stop being valid when the calendar turns. A currency rule is a practical judgement about how likely the person, or the norms, have moved since. Our guide to what makes an IQ test reliable lists the reliability figures of the main tests, and how IQ tests work explains the method.

How long do schools and agencies accept an IQ score?

There is no universal number. Two rules written down in public documents show the typical scale.

Note what the second rule says about age. Scores from before 16 age out and scores from 16 onwards do not, because ability settles through the teens. The same guidance says an IQ score more than six months beyond its window should not be used to decide whether a child meets the disability listing. Other bodies set their own limits: societies, school districts and universities each decide which tests and which dates they accept (see Mensa IQ score requirements and high-IQ societies). An online quiz has no norm sample for a score to be current against; our guide to the official IQ test covers what a recognised result needs.

How stable is an IQ score over the years?

Fairly stable in adults and less so in children. A meta-analysis of longitudinal studies found adult rank order stable at about .76 across five years (Breit and colleagues, 2024). That is high and not perfect: some people move up, some move down, and extreme scores drift back toward the average. Our guide to the most accurate age to take an IQ test covers why early-childhood scores move more than adult ones.

The arithmetic of regression to the mean shows what that means for a retest: the expected second score is 100 plus the correlation times the distance of the first score from 100.

The averages hide a spread: individual retests land on either side of them. Our pages on regression to the mean and IQ score margin of error explain both effects.

Why does an IQ score change between tests?

• Measurement error. Every score carries a standard error, about 2 to 3 points on the main full-scale batteries, so two sittings rarely match exactly.
• Practice. A second sitting of the same test raises scores by about .26 standard deviations, roughly 4 points, and more with coaching (Hausknecht and colleagues, 2007).
• Regression to the mean. An extreme score contains some luck, and the retest drifts back (see the table above).
• The age of the norms. Raw performance rose about 0.28 points a year in a meta-analysis of 271 samples from 1909 to 2013, with slower gains lately (Pietschnig and Voracek, 2015). Publishers re-norm tests to stop it; see why IQ norms expire.
• Real change. Development in childhood, and events such as a head injury, can change what a person can do (see can a concussion lower your IQ).

Treat the table as arithmetic, not a conversion. It shows why a score from a decades-old edition is not the same claim as a score from a new one, and why the IQ score converter is for like-with-like comparisons only.

When is it worth taking an IQ test again?

• A decision needs a current score. When a school, agency or court asks for a score newer than yours, use its window; for special education that is three years.
• The test has a new edition. A newer edition has fresh norms; see WAIS-IV and WAIS-5 index scores.
• Something has changed. A head injury, an illness or a long gap in childhood can justify a fresh look.
• Not for curiosity. Retesting soon after adds practice effects of about 4 points on the same test, and special-education rules cap re-evaluation at once a year unless both sides agree.
• Use a recognised test. Take a supervised, norm-referenced test (see how to read an IQ test report), and compare scores only on the same scale.

How long a test takes to sit is a different question; how long an IQ test takes covers the clock, from a short screener to a full battery.

Quick answers about how long an IQ test is valid

• How long is an IQ test valid? There is no fixed time. US special education re-evaluates at least every 3 years, and the SSA treats child scores as current for 1 to 4 years.
• Is an IQ result valid for life? It stays a true record of that day, and an adult score from age 16 can be treated as current indefinitely if it fits present functioning.
• Do IQ scores change over time? A little. Adult rank order is stable at about .76 across five years, and individual scores move by chance, practice and the age of the norms.
• How often should you retest? Only when a decision needs a current score, the test has a new edition or something has changed, and no more than once a year without agreement.
• Does an old IQ score still count? For an adult, often yes; each school, agency or society sets its own limit.
• Is an online IQ test result valid? Only if the test has a norm sample and a stated standard deviation; most quizzes have neither.
• How long does an IQ test take? That is a separate question, covered in our guide to how long an IQ test takes.

Sources

• Breit, M., Scherrer, V., Tucker-Drob, E.M. and Preckel, F. (2024): The stability of cognitive abilities: a meta-analytic review of longitudinal studies, Psychological Bulletin, 150(4), 399-439.
• Pietschnig, J. and Voracek, M. (2015): One century of global IQ gains: a formal meta-analysis of the Flynn effect (1909-2013), Perspectives on Psychological Science, 10(3), 282-306.
• Hausknecht, J.P., Halpert, J.A., Di Paolo, N.T. and Moriarty Gerrard, M.O. (2007): Retesting in selection: a meta-analysis of coaching and practice effects for tests of cognitive ability, Journal of Applied Psychology, 92(2), 373-385.
• Strenze, T. (2007): Intelligence and socioeconomic success: a meta-analytic review of longitudinal research, Intelligence, 35(5), 401-426.
• US Department of Education, 34 CFR 300.303: Reevaluations, paragraph (b), limits on frequency (once a year; at least every 3 years).
• Social Security Administration, Program Operations Manual System DI 24583.060: IQ score currency, parts C.1 and C.2.
• Reliability and standard-error figures are those in our own guide to what makes an IQ test reliable. Retest and old-norm figures are computed from the correlations and rates shown.