Standard-rated supplies
Standard rated supplies are goods and services that are charged VAT at the standard rate of 15%. Most goods and services are standard rated unless they are listed under the following categories:

Working out how much VAT to charge or claim
If you know the VAT-exclusive price, and you want to work out the VAT amount and the VAT-inclusive price, you multiply the VAT-exclusive price by the standard-rate of VAT, currently 15%.

If you know the VAT-inclusive price, and you want to calculate the amount of VAT to pay or reclaim and also the VAT-exclusive price, you multiply the VAT-inclusive price by the standard-rated VAT fraction, currently 3/23.

An invoice number which is unique and sequential
The tax point i.e.the time of the supply
The date of issue of the invoice
The seller’s name, address and VAT registration number
The customer’s name or business name and address
A description of the goods or services supplied
For each description, the quantity of the goods or the extent of the services, the rate of VAT and the amount payable, excluding VAT, expressed in any currency.
The gross total amount payable, excluding VAT, expressed in any currency
The rate of any cash discount offered
The total amount of VAT chargeable, expressed in sterling
The unit price
Where a margin scheme applies, an indication that a margin scheme has been applied
Where a VAT invoice relates to a supply where the customer is liable to pay tax, an indication that the supply is one where the customer is liable for tax.

Retailers are only required to issue a VAT invoice if the customer asks for one.