Best Before Two Years? The Thin Evidence Behind Expiring English Test Scores

Most major English proficiency tests recommend that score users accept results for a period of two years. This paper examines the evidence on which this recommendation rests. Very few publicly available documents set out a rationale for the two-year period, and the most detailed of them (Powers & Lall, 2013) acknowledges both that the choice of an exact date is somewhat arbitrary and that existing research could not fully justify any expiry policy. A review of the second language attrition literature shows little evidence of a substantial decline in proficiency within two years, particularly among more proficient learners, although this literature is too limited to support an alternative figure. I then suggest that the growing use of AI tools, which may be changing how much English people use and in what ways, provides a further reason to reconsider the policy, even though the direction of this effect is not yet clear. The paper concludes with a research agenda rather than a proposal for a new validity period.