In general, attorneys operate on one of four bases: Agree on a service arrangementīilling in the legal world is not always cut-and-dry. Like any invoice, this one should also provide complete contact information for both the client and attorney, including full names, addresses, and phone numbers. Payment due date and penalties for late payment.The subtotal for all services, taxes due, and total balance due.Billing rate by service, and the total due for each service provided.This invoice is a record of work and a formal request for payment. The attorney would track the time spent on various services provided on their client’s behalf whether it would be a contingency case or all fees would need to be paid in advance depending upon the type of case. A lawyer/attorney legal invoice is a document that would be used to bill a client for legal services rendered.