Currently no study has systematically investigated how second language learners (L2) with specific learning difficulties (SpLDs) benefit from extended time in L2 assessment. Research in this area is needed because judgements about time extensions are often based on intuitions rather than on research evidence. This study investigated the effect of different timing conditions on the L2 reading performance of adolescent learners of English who demonstrate different first language (L1) literacy profiles. It aimed to uncover whether Hungarian L2 learners who have below average L1 reading comprehension and word-decoding skills, which can be indicative of SpLDs, gain from time extension differentially in the reading component of the Aptis for Teens test from those whose L1 skills are in the average or above average range. Our generalised linear mixed-effects model predicted no significant effect of the time extension and no interaction between time extension, L1 skills and test tasks. This suggests that time extension did not boost students’ scores and did not confer a differential advantage for students with low-level L1 skills either. Our results confirm the importance of universal test design and providing a generous margin of around 50% extra time from the mean test population completion time for all test-takers.