What is the smallest payment amount I can make on an installment agreement to the IRS?

The smallest payment amount you can make on an IRS installment agreement is determined by the negotiations you, your lawyer or a judge carries out with the IRS. The IRS approaches this determination using an "allowable living expenses" measurement for your geographic area and family size. Any amount not qualifying as an allowable living expense will be handed over to the IRS each month. However, you and your attorneys can argue for a lower sum. You will have to prove the sum the IRS has requested would place undue hardship on you, your family or your financial situation.