Foreign currency transactions and foreign exchange gains or losses

Key requirements

Foreign-currency tax invoices show the required net, GST and gross Singapore-dollar amounts. The chosen approved source is updated at least quarterly and used consistently for the prescribed year. Input tax follows the supplier’s Singapore-dollar GST or Customs permit, not a different book exchange rate. Net realised exchange gains or losses are reported at absolute value in exempt-supplies Box 3; year-end translation differences are excluded. An alternative including realised and unrealised amounts requires the specified consistent accounting basis and can affect de minimis input recovery. Keep currency conversion separate from the supply’s original GST classification.