Nigeria awards upstream licences to foreign investors under production sharing contracts (PSC). Nigerian PSCs are primarily governed by the 1969 Petroleum Act, 1959 Petroleum Profits Tax Act and the 1999 Deep Offshore and Inland Basin Production Sharing Contracts (DOIBPSC) Act. The main PSC parameters are cost recovery and profit sharing based on an R-factor. Royalty rates are based on water depths. In November 2019, the government amended the DOIBPSC Act, introducing an oil royalty of 10% in deep offshore fields, with an additional price sensitive element, ranging from 0% to 10. Corporate income tax for oil (known as Petroleum Profits Tax) is based on the block's location and is reduced for the first five years for new investors.