While invoices don’t need to be signed, there are reasons why getting signatures on invoices can be a good thing. Signed invoices help protect you and your clients from misunderstandings. When there are no signatures on invoices, they’re just written requests for payment. They can't be used as legal proof. So, if you want your invoices to serve as legal documents in disputes, do ask your clients for their signatures on the invoices. It’s the only way to prove that both you and your customers agreed to payment and understood the invoice's terms. Signatures serve as evidence that someone read, understood, and agreed to the document’s terms. Collecting payment from a signed invoice is much easier than from an unsigned one because the customer is liable to pay the invoice without questioning the terms.