This paper conducts an impact evaluation of the effects of two tax administration interventions—a taxpayer register expansion and education programme, and a new electronic filing system for presumptive tax—on the number of small business taxpayers and presumptive tax revenues in Uganda. Using a difference-in-differences approach and administrative data covering both presumptive taxpayers and comparable small corporate income taxpayers, we find that the number of small business taxpayers filing tax returns and presumptive tax revenues increased substantially after the interventions. We argue that the interventions complement each other because both interventions were established around the same years, and the taxpayer register expans...