A payment installment plan is an agreement between you and the Illinois Department of Revenue to pay your tax delinquencies using a monthly payment plan. THIS MASTER RENEWABLE ENERGY CREDIT PURCHASE AND SALE AGREEMENT (the.Get up and running quickly with a master service agreement template Illinois. This downloadable template will get you selling in no time. "Scheduled Payment" shall mean each scheduled monthly payment of principal and interest on a Loan. "Seller" shall have the meaning set forth in the preamble. However, any provision in an installment sales contract that forbids the buyer to record the contract or a memorandum of the contract is void and unenforceable. A master purchase agreement is a legally binding contract between buyer and seller, and typically relates to buying and selling goods rather than services. Sample Business Contracts. Installment Sales Contract Act.