Please refer to the MAS website for exchange rates data.
For tax purposes, please note that the average rate of exchange to be used for any year of assessment (YA) is the sum of the total end-of-month rates for the relevant basis period, divided by the number of months within the basis period. For example, for a company newly incorporated in Mar 2022, with its first basis period from Mar 2022 to Dec 2022, the average rate of exchange to be used for its YA 2023 tax return should be the sum of the total end-of-month rates from Mar 2022 to Dec 2022, divided by 10.
(NEW!) You may use the Exchange Rate Search Function (XLSX, 278 KB) to retrieve the average exchange rate (computed using data extracted from the MAS website) and to convert the foreign currency amount to Singapore dollars for YA 2020 onwards.