456. An official agent may authorize, in writing, an advertising agency to incur or order election expenses up to the amount he fixes in the authorization. The amount may be changed in writing by the official agent before he files his return of election expenses. However, the official agent shall not reduce the amount below the amount of the election expenses already incurred or ordered according to law by the advertising agency.
The advertising agency shall furnish to the official agent, within 60 days after polling day, a detailed account of the expenses incurred or ordered, accompanied with the vouchers and advertising proof, including the invoices of subcontractors.