Article 1 of the Chilean Mining Code states that "The State has absolute, exclusive, inalienable and imprescriptible ownership of all mines" but goes on to say that anyone may prospect for and establish concessions or mining rights for the search or mining of substances. As well as the Mining Code, foreign investors have to observe Decree Law No. 600 which deals with foreign investment and investment contracts. This allows tax invariability for 10 years from start of production, access to the foreign exchange market and the right to return capital actually brought into the country without being taxed. The tax invariability can be extended to 20 years for companies bringing in US$50 million or more. In return for these concessions foreign investors have to pay a combined tax rate of 42% compared with the current 35%. They may change, but once only, to the current mining tax regime but most have opted for the higher tax rate because gives more certainty to financial planning.