Upstream licences for the international oil companies (IOCs) are awarded under Production Sharing Contract (PSC) terms through licensing rounds and direct negotiations. The PSCs predominantly apply to offshore projects, while most of the onshore licences are awarded to the national oil companies (NOCs) under concession terms. State companies have the right to take a minimum working interest of 51% in any commercial development. Past exploration costs incurred by an IOC are not reimbursed by the state, but may be recovered from the share of production. Cost recovery ceilings and profit oil splits vary by area and hydrocarbon type, based on a sliding scale rates linked to production. Profit oil splits are negotiable, while cost recovery ceilings are set for each licensing round. Resource tax, corporate income tax, special oil levy, export duty and a range of bonuses, rentals and fees are payable.