Sch 9ZD para 12
(1) An OSS scheme return is to be made out in sterling. (2) Any conversion from one currency into another for the purposes of sub-paragraph (1) is to be made using the exchange rates published by the European Central Bank— (a) for the last day of the reporting period to which the OSS scheme return relates, or (b) if no such rate is published for that day, for the next day for which such a rate is published. (3) An OSS scheme return— (a) must be submitted to the Commissioners before the end of the month following the month in which the last day of the reporting period to which it relates falls; (b) must be submitted by such electronic means, and in such form and manner, as the Commissioners may direct (by means of a notice published by them or otherwise) or may by regulations require.