I am self-employed and just started a business. Is it a legal requirement to produce an invoice and receipt for my clients? Will HMRC expect to see these next year when I file my SA? Thanks, Mark
An invoice should indicate what is owed, and for what. If you want to prove they owe you money, an invoice is a typical first step, no matter what country you're in. Even if you just use a free Invoice template (for example, through Microsoft Excel), it at least gives you a record of what payments to be expecting.
As you get to larger companies, they won't pay just based on an email - they'll want an invoice to pass through to their Accounts Payable department.
(IANAL) It is not a legal requirement to create an invoice or receipt, but doing so shows you're a serious entrepreneur who knows how to run a business. When I invoice, it gets sent as a PDF to their email, detailing what work I did and how much I expect, along with terms of payment. Then, when I get paid, I email them the invoice with the payment amount added, so they can see they owe nothing after. Optionally, I could email a receipt, but I feel that with the amount of work I do, attaching the payment amount to existing invoices makes it easiest for any accounting department to see why money went to me.