Home1998 Treaties and Agreements ...Sao Tome and Principe (12985) – Investment Incentive Agreement hide Sao Tome and Principe (12985) – Investment Incentive Agreement TIAS Office of Treaty Affairs September 10, 1998 Finance: Investment Guaranties Agreement signed at Washington September 10, 1998; Entered into force September 10, 1998. Download attachment [286 KB] Tags Finance Sao Tome and Principe Treaties