Our Terms of Sale are Net 15 and it is not contingent on when you receive payment. Invoices will be mailed to you promptly. To maintain a good credit history and to assure continued open account terms, it is important that all checks are mailed within 30 days from date of invoice. Invoices not paid in full within thirty (15) days of the date of invoice will accrue interest at the rate of 1 1/2% per month (18% per annum) on the unpaid balance. The failure to make timely payments may result in no further credit being granted. Payments on account will be applied first to any outstanding interest, then principle.