As a condition of your agreement, any refund due you in a future year will be applied against the amount you owe. Therefore, you may not get all of your refund if you owe certain past-due amounts, such as federal tax, state tax, a student loan, or child support. The IRS will automatically apply the refund to the taxes owed. If the refund does not take care of the tax debt; you must continue the installment agreement.

Source: www.irs.gov