You can get a VAT refund if you shop at stores that participate in the Retail Export Scheme. (Signs are posted in the window.) When you make a purchase, show your passport and request a Retail Export Scheme form (VAT 407) and a stamped, pre-addressed envelope. Show the VAT form and your sales receipt to British Customs when you leave the country -- they may also ask to see the merchandise. After Customs has stamped it, mail the form back to the shop in the envelope provided before you leave the country. Your VAT refund will be mailed to you.
Remember: Keep your VAT forms with your passport; pack your purchases in a carry-on bag so you'll have them handy; and allow yourself enough time at your departure point to find a mailbox.
Several readers have reported a VAT refund scam. Some merchants allegedly tell customers they can get a refund form at the airport on their way out of the country. This is not true. The form must be completed by the retailer on the spot, or you won't get a refund later.
For information, contact Global Refund, 707 Summer St., Stamford, CT 06901 (tel. 800/566-9828; www.globalrefund.com).