Objective: To determine the economically adequate fertilization dose for a castor bean (Ricinus communis L.) crop that improves the producer's benefits using the partial budgeting technique. Design / methodology / approach: The experiment was established at a site located 500 m from the Centro de Chiapas experimental field, with an altitude of 800 m. Two production factors were studied: nitrogen (40, 60, and 80) and phosphorus (20, 40, and 60) with three levels each. The treatments had nine combinations in a randomized complete block experimental design and four replications. Phenological and morphological variables, seed yield, and variable costs economic components were evaluated as a response. Results: With the average yields the obtained net benefits were determined; an adjustment of the benefits was made, and its dominance was determined. Four experiments were dominated, and five showed favorable profits for the producer. The 80-60-00 formulation had a return rate (RR) of 23 %. Conclusions: The 40-20-00, 40-40-00, 40-60-00, 80-40-00 and 80-60-00 formulations were dominant. The 80-60-00 formulation reported the highest RR, an increase in variable cost of US$9.64, like other doses of lower costs and benefits. For this dose, the net benefits increase was us$ 222.61.