DUBLIN, May 21 (Reuters) - Ireland believes September and October will be the key period for agreeing international tax reforms, Finance Minister Paschal Donohoe said on Friday, reiterating his concerns over a global corporate minimum tax rate. Donohoe said he had reservations about a “high” minimum tax rate on the basis that it could be a step towards global tax harmonisation rather than addressing aggressive tax planning. He added that small countries such as Ireland needed to be able to use tax policy as a legitimate policy tool. “I think the period September to October will be a particularly important period in laying out what kind of change is in prospect for years to come,” Donohoe told a virtual conference in a pre-recorded interview. (Reporting by Padraic Halpin; Editing by Alison Williams) Our Standards: The Thomson Reuters Trust Principles.