411. Every official agent may authorize, in writing, an advertising agency to incur or order election expenses up to the amount he fixes in the authorization. That amount may be changed at all times, in writing, by the official agent, before he files his return of election expenses.
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. The account must be made in the form prescribed by the chief electoral officer.