This is a final 'letter of claim' (also known as a 'letter before action'), demanding payment for an overdue invoice(s). In this letter you threaten court action if you don't get a response.
The letter calculates the total outstanding debt, including, in some cases, any interest due on the overdue amounts. It also includes the information sheet, reply form and financial statement form that you need to provide before you can go to court.
Use this letter only if you have sent one or more invoices to a person or organisation for goods supplied or services performed in the UK. Ideally you will have sent at least one previous letter of demand.
It cannot be used if the recipient has disputed your claim for payment. In England and Wales, you also can't use it during any 'breathing space' period that they may have been granted under the Debt Respite Scheme.