Letters that might precede a dollar sign

• Letters to a creditor
• Promise-to-pay note
• What a pot may hold
• Letters before a monetary amount
• Payback note?
• Promissory note, of a sort
• "Will Venmo you later"
• Letters indicating a debt
• Written declaration of a debt

Wikipedia Word definitions in Wikipedia
An IOU (abbreviated from the phrase "I owe you") is usually an informal document acknowledging debt . An IOU differs from a promissory note in that an IOU is not a negotiable instrument and does not specify repayment terms such as the time of repayment. ...