Here are the full rules:
Customs duty - customs duty becomes payable if the goods are over £135 in value but is waived if the amount, when calculated is less than £9.
The amount of customs duty charged will depend on the type of goods imported and the value stated on the customs declaration CN22/CN23 (converted to £sterling using the rates of exchange for the month of importation as shown on the HMRC website).
The percentage varies depending on the type of goods and their country of origin. Duty is charged on:
the price paid for the goods, plus;
any local sales taxes, plus;
postage, packing and insurance.
However, the cost of postage is excluded from the calculation for customs duty on gifts except where the sender has used the Express Mail Service (EMS) as opposed to a standard mail service.
Where the value of gifts is below £630 per consignment, a flat rate of duty of 2.5 per cent will be applied, but only if it is to your advantage.
Value Added Tax (VAT) - Import VAT is charged at the same rate that applies to similar goods sold in the UK and applies to commercial goods over £15 in value, and on gifts that are over £40* in value. However, please note that commercial consignments sent to the UK from the Channel Islands do not benefit from any relief of import VAT. The value of the goods for import VAT is based on the:
basic value of goods, plus
postage, packing and insurance, plus
any import (Customs or Excise) duties charged.
As with customs duty, the cost of postage is excluded from the calculation for VAT on gifts except where the sender has used the Express Mail Service (EMS) as opposed to a standard mail service.
*Please note this limit will reduce to £36 with effect from 1 January 2013.