Value Added Tax, or VAT, is the European equivalent of sales tax in the United States. A certain percentage is added to the sales total for taxable goods and purchases. Under certain circumstances (for example, if you are a VAT-registered business owner), you can apply to Her Majesty's Revenue and Customs (HMRC) to get the VAT you paid refunded to you. To claim your VAT back, however, you need to know the VAT Tax Identification Number (TIN) of the business that sold you the goods or services.
Find the invoice for the transaction. The VAT number has to be written on the invoice by law. If you have a lengthy invoice, be sure to scrutinise it.
Call the business and ask for a copy of the VAT receipt. The business may also be willing to give you the VAT number over the phone.
Call the National Advice Service at 0845-010-9000. The representative may be willing to provide you with the VAT number, or he can provide you with information about what to do next if you don't have the number. If you are calling the advice centre internationally, dial your country's exit code (011 from the United States), the country code (44 for the United Kingdom) and then the number. The number to dial from the United States would be 011-44-845-010-9000. (The leading zero is dropped from the area code when dialling from abroad.)
A business does not have to supply a VAT invoice for every transaction. If you don't identify yourself as a VAT-registered customer at the time of sale (in which case, the business is obligated to give you a VAT receipt with its VAT number in it), you may not be able to get a receipt after the fact. Therefore, it may be too late to recoup the VAT. (You cannot claim the VAT back without the VAT number.)