The grounds for reimbursement listed in R. 103(1) EPC aside, fees may also be refunded if there was no legal ground for their payment, e.g. in the event of payment by mistake or overpayment, see Art. 12 RFees e contrario (T 1284/09).
Source: http://www.epo.org/law-practice/legal-texts/html/caselaw/2019/e/clr_v_a_9_3_6.htm
Date retrieved: 17 May 2021