AbstractTechnical assistance and increased use of ICT in tax administrations hold promise for greater revenue collection. Yet, the evidence on how these activities work in the real-world circumstances of developing countries is scant. The paper attempts to fill this gap by evaluating an intervention undertaken jointly by the Finnish and Tanzanian revenue administrations. The programme introduced a new risk-based case selection method for enhancing the effectiveness of firm tax examinations in Tanzania complemented by supplementary staff training and developing management practices. Our results, stemming from a difference-in-differences analysis and administrative data from the Tanzanian Revenue Authority, indicate that the intervention increased the corrected amount of taxable income by approximately 20% during the first year of the new approach.