How do I collect an unpaid consulting invoice?
How to collect an unpaid consulting invoice
Short answer
The hardest consulting collection situation is when the advice has been delivered and accepted, but the client decided after the fact that they don't like the outcome. Your protection is a signed statement of work, a completion acknowledgment, and milestone billing. Once those are in place, the standard collection sequence applies: call at day 3, written notice at day 14, escalation at day 30.
Consulting invoices typically go unpaid for one of these reasons: the client hit cash flow problems, they're disputing the value or quality of the advice, or they're avoiding the issue and hoping it goes away. The first is a payment plan situation. The second is a dispute that needs a written response. The third responds best to direct phone contact. Most clients avoiding an invoice will eventually pick up or respond to a persistent but professional follow-up sequence.
The signature protection for consulting work is a completion acknowledgment. A short email or document at the end of an engagement that says, in effect, "here's what we delivered, please confirm receipt." Getting the client to reply ("confirmed, thank you") creates a record that the work was delivered and accepted. A client who later claims the work was not performed has a much harder case if they sent you a confirmation email.
Retainers are the most reliable solution for consultants who bill regularly. A monthly retainer on automatic ACH or card billing means payment happens before the month's work is delivered, or at least at the same time. That inverts the risk. Instead of hoping the client pays after receiving value, the client has already paid for access to your time in the coming month.
For invoices that are genuinely past due and not responding to follow-up, a well-written demand letter from the consultant (not a collections agency) is often more effective than in other industries. Reputation matters in consulting relationships. A letter that explicitly states you will pursue small claims court or, if true, report non-payment to their professional network can motivate action that routine reminders don't.