A tax period is the period for which return is required to be furnished. Thus, a taxpayer can claim refund of unutilised ITC on monthly basis.Here's when you can claim a GST refund: Due to mistakes or omissions, excess tax is paid. Dealer and deemed export goods or services under the claim of refund or rebate. Purchases made by UN bodies or embassies can be refunded.Under GST, the applicant should file GST refund claims within 2 years from the relevant date. If the claim is in order, the refund has to be sanctioned within a period of 60 days from the date of receipt of the claim.