The assessment of everyday cognition is crucial in cognitive training research to determine whether a training intervention has real-world effects in improving everyday-life functioning. Yet, objective measures for everyday cognition are limited. The Everyday Problems Test (EPT; Willis & Marsiske, 1993) is a pen-and-paper test that assesses everyday cognition in adults along seven scales related to the Instrumental Activities of Daily Living (IADL; Lawton & Brody, 1969). However, not all EPT items are up-to-date and relevant nowadays and the original validation focused exclusively on older adults using a test-retest interval of one year. Cognitive training studies often test adults from young to old age and use shorter intervals to assess and compare performance before and after training. Therefore, we constructed a computer-based short form of the EPT and assessed its validity and test-retest reliability across the entire adult lifespan. We updated or created items spread evenly across the IADL scales with a range of varying difficulties. Consequently, we administered a 14-item online version of the EPT along with sociodemographic questions (e.g., on education) and questions regarding IADL performance to 180 adults situated in the UK, stratified into three age groups: young (18-39 years), middle-aged (40-59 years), and older adults (60-85 years). Two weeks later, participants were invited to re-conduct the EPT. We will discuss the validity of this 14-item EPT and its relation to age, education and IADL performance, as well as its test-retest reliability and applicability in cognitive training studies.