Purpose: This study aims to investigate how judgments of firms’ underlying motives are affected by corporate social responsibility (CSR) communication which features percentages of profit allocations to CSR causes. It also examines how firm size interacts with CSR spending allocations affecting motive attributions for firms of different sizes. Design/methodology/approach: Two experiments were carried out manipulating CSR spending allocations (smaller vs larger percentage of profit) and firm size (small vs large firm). Findings: A larger percentage of profits allocated to CSR enhanced value-driven motives and inhibited inferences of manipulative intent, which produced lower egoistic-driven motives. Large firms allocating smaller percentages to CSR were judged as less value-driven and were more prone to elicit manipulative intent. Originality/value: Two routes of motive attributions were identified – a direct route, contingent on CSR spending allocations and firm size; and an indirect route via inferences of manipulative intent, which inhibited favorable motives and prompted unfavorable ones. Both routes resulted from numerical cognition associated with the processing of numbers. Managerial implications include suggestions for firms wishing to overcome negative consumer bias arising from communication featuring CSR spending allocations and firm size.