If you give customers a refund or credit for all or part of an amount they paid or were charged for goods they return, you may adjust, refund, or credit the customer the GST/HST you first charged or collected on these goods. If you do this, you have to issue a credit note to the customer, or have the customer issue a debit note to you.
Be sure the following information is included on the credit or debit note:
either
You can deduct the amount of GST/HST adjusted, refunded, or credited in determining your net tax for the reporting period in which you issued the credit note or received the debit note, as long as that amount was previously included in your net tax. In turn, if your customer claimed an input tax credit (ITC),he or she will add that amount in calculating his or her net tax. If your customer claimed a rebate, he or she will repay that amount.
You have four years from the end of the reporting period during which you reduced the purchase price to make the adjustment, refund, or credit.
If you refund only a certain percentage of the purchase price (for example, 85%) and keep the balance as a restocking charge, you will refund only that percentage of the GST/HST you first collected. You issue a credit note, or the customer issues a debit note, for the amount of GST/HST you refund.
If you and the customer are GST/HST registrants, you can choose not to refund or credit the customer the GST/HST that was previously paid. You may wish to forgo the GST/HST refund if you have already remitted the tax and the customer has already claimed an ITC. In this case, you simply refund the amount without including the GST/HST that the customer first paid. You and your customer do not have to make any adjustments on your GST/HST returns.