If you use the VAT flat rate scheme or are considering using it you could get a nasty shock.
New rules from 1st April could cost you several thousand pounds a year extra. And moving to the standard VAT scheme will still be expensive!
If you are registered for VAT you must set out your sales invoices in a particular way. If your customer is VAT registered, they will need a valid VAT invoice for them to be able to claim VAT back and by law you must send them one.