Reimbursement of benefits wrongly rendered

(1) Insofar as an administrative act has been set aside, benefits already rendered must be reimbursed. Benefits in kind and services are to be reimbursed in money.
(2) Insofar as benefits have been wrongly rendered without an administrative act, they must be reimbursed. Sections 45 and 48 apply correspondingly.
(2a) The amount to be reimbursed bears interest, from the point in time an administrative act becomes ineffective on the basis of which benefits for the promotion of institutions or similar benefits were rendered, at five percentage points above the base rate per annum. Recourse to the interest claim may in particular be dispensed with where the beneficiary is not responsible for the circumstances leading to the withdrawal, the revocation or the ineffectiveness of the administrative act, and renders the amount to be reimbursed within the period fixed by the authority. Where a benefit is not used for the determined purpose soon after payment, interest under the first sentence may be demanded for the time until it is used for that purpose; the same applies insofar as a benefit is drawn on although other funds must be used proportionately or in priority; section 47(2), first sentence, no. 1 remains unaffected.
(3) The benefit to be reimbursed is to be fixed by written administrative act. The fixing should, where the benefit was rendered on the basis of an administrative act, be combined with the setting aside of the administrative act.
(4) The claim to reimbursement becomes time-barred after four years from the end of the calendar year in which the administrative act under subsection (3) became unchallengeable. For the suspension, the suspension of expiry, the fresh commencement and the effect of limitation, the provisions of the Civil Code apply correspondingly. Section 52 remains unaffected.
(5) Subsections (1) to (4) apply correspondingly to corrections under section 38.