Validating contractor invoices
If the client or agency refuses to pay then you have to follow the correct late invoice payment process to collect your debts and the money owed to you.
Here is a list of the legal requirements for invoices in the UK.
These are all included on our invoice templates at the bottom of this page.
Company details: The following information should be included on all your invoices: Invoice number: Each of your invoices should have a unique invoice number.
Although is called a number it can include letters.