Unfortunately, I have reached the point where I require payment at the time of measurement (with rare exceptions when dealing with a repeat customer with a good payment record). I just got tired of waiting months for payment and while I've never been "stiffed", I did have to take one guy to small claims court after waiting about 18 months for payment If you ever do this and if the organization is a corporation make sure to send the paperwork to the Registered Agent of the corporation. In the case above, the RA was the late Jesse Helm's law firm. I had payment within two days of them receiving the paperwork. In my experience, not-for-profits are the worst when it comes to timely payment.