Following up right away on late payments, asking late-paying customers for feedback and visiting late-paying clients personally are some suggestions for collecting unpaid invoices, note Small Business Bonfire. If these things fail, hire a collection agency or attorney.
The longer an unpaid invoice is ignored, the less likely it is to ever be paid. If the decision is made to bring in outside help to collect the debt, compare the fees and services provided by a collection agency to the fees and services of an attorney. The collection agency will sometimes cost more to collect on the unpaid invoice than the attorney, notes Avvo, because the collection agency hires both collection agents and attorneys.