A letter written to someone who owes money should have a first sentence that details the reason for the letter, with subsequent sentences offering supporting statements and a method or methods of resolution. The letter's closing should thank the recipient. Such letters should be direct; polite and professional; written and addressed to the correct person; and sent as soon as possible, according to Michelle Dunn for About.com.
Dunn explains that the first sentence of the letter should list the balance owed, the work done, and when the money was due. For example, "This letter is a reminder that you owe $250 as of November 1 for brake work performed on your car on October 18."
Next, the letter should outline possible ways of resolution and an incentive to pay, such as an enclosed envelope and/or a statement that if payment is made by a certain date, no interest charges will be added. Enclosing a self-stamped envelope for payment removes one step and may encourage a recipient to pay right away, notes Dunn. An important step is making sure the letter goes to the right person. If the letter is sent to a business, it is possible that the contact person for the work is not the person responsible for payment.