The exploitation stage, upon declaration of commerciality, is 25 years long with optional 5 + 5 year extensions. The adopted concession scheme is royalty and tax based lease agreement. Royalties on production are linked to the ratio R/C where R is cumulative revenue and C is cumulative costs. Royalty is deductible for the purposes of assessing income tax. The corporate tax rate is 20% and the regional tax is 5%, applied without any additional ordinary or extraordinary contribution or duty in favor of the State or other third party.