Kazakhstan experienced significant modifications to its education system in response to the outbreak of COVID-19, involving widespread school closures in the 18 months between March 2020 and September 2021. The purpose of this study is to estimate the loss of learning for seven different subjects due to the pandemic restrictions. Based on a large sample of selective school applicants over the past decade (N = 161,971) and a series of equated standardized assessments, extrapolatory analysis revealed substantive COVID-19-induced learning loss for all seven test subjects of interest. The study identified very large learning losses in Kazakh and Russian literacy (whether as a 1st or 2nd language) and more moderate losses in mathematics, quantitative reasoning, and ESOL ability. We speculate on the reasons for the differences in effect sizes and provide implications for future policy and practice, with a particular focus on planning for remedial education programmes.