The aim was to assess the incremental costs of chimeric antigen receptor (CAR) T-cell therapy (axicabtagene ciloleucel, tisagenlecleucel) compared with standard of care in adult patients with relapsed or refractory diffuse large B-cell lymphoma (r/r DLBCL) from the German third-party payer perspective. A budget impact model was established over a 6-year period. Estimation of the third-line population: partitioned survival model based on outcome data from peer-reviewed literature, a top-down approach based on population forecasts, and age-standardized incidences. Cost data were derived from the controlling department of a tertiary hospital and a German cost-of-illness study. In the scenario analysis, the budget impact of treating second-line DLBCL patients was calculated. One-way deterministic sensitivity analyses were conducted to test the robustness of the model. For the period 2021-2026, 788-867 (minimum population, min) and 1,068-1,177 (maximum population, max) adult third-line r/r DLBCL patients were estimated. The budget impact ranged from €39,419,562; €53,426,514 (min; max) in year 0 to €122,104,097; €165,763,001 (min; max) in year 5. The scenario analysis resulted in a budget impact of €65,987,823; €89,558,611 (min; max) and €204,485,031; €277,567,601 (min; max) for years 0 and 5, respectively. This budget impact analysis showed a significant but reasonable financial burden associated with CAR T-cell therapy for a limited number of patients requiring individualized care. Further, this study presents challenges and future needs in data acquisition associated with cost analysis in personalized medicine. For comprehensive economic discussions, complementary cost-effectiveness analyses are required to determine the value of innovative therapies for r/r DLBCL.