For a person residing in UAE, it is not possible to claim Tax Refund. However for a tourist who's visiting Dubai, he can claim tax refund provided the invoice is issued on the date the goods are collected in person by the tourist at a physical store, and the Tax Free Tag issued and attached to it on the same day. If the tourist pays online, the invoice must clearly state that it is an advance / deposit / booking fee and when collectiing the goods the actual sales invoice is issued on the day. Otherwise it is not possible to purchase online and claim tax free refunds.