CPP-1 Form: Filing, Submission, and IDOR Payment Terms

The CPP-1 form is the Illinois Department of Revenue’s “Installment Payment Plan Request,” and you file it when you owe Illinois state tax you cannot pay in full and want to break the balance into weekly, biweekly, or monthly payments. Both individuals and businesses use the same form, and it covers most Illinois tax types, including individual income tax, business income tax, sales tax, withholding tax, and excise tax.¹

One structural rule to know up front: individual income tax cannot be combined with other tax types on a single CPP-1. If you owe both, you file two separate forms. Other tax types can share one form.¹

Before You File

You must have filed every required Illinois tax return through the current date. IDOR will not process a CPP-1 while returns are outstanding, so catch those up first.²

There is no hard due date for the form itself, but IDOR asks you to send it within 10 days of receiving a bill or notice you cannot pay. Waiting invites additional penalties and possible enforcement action before you have an agreement in place.²

What Goes on the Form

The CPP-1 has four steps. Individuals enter their Social Security number, name, and contact information, adding a spouse’s SSN if the liability is shared. Businesses enter their FEIN, Illinois account ID, and legal name.³

The substance is in Step 2, where you describe the debt and propose the plan:

Every tax period covered by the debt (month, quarter, or the tax year from the return).
A good-faith down payment, due when you submit the form. You can pay it through MyTax Illinois, by phone, or by check.
The remaining balance the plan will cover after the down payment.
A proposed start date, payment amount, and frequency (weekly, biweekly, or monthly).

If your unpaid liability is more than $15,000, attach a financial disclosure: Form EG-13-I for individuals or Form EG-13-B for businesses. These forms detail your income, expenses, assets, and liabilities so IDOR can judge whether the payment amount you propose is realistic.¹

Step 3 is banking information: institution name, routing number, and account number. Completing it authorizes IDOR to pull payments by ACH debit at the frequency you chose, and if you have a checking or savings account, ACH debit may be required as your payment method. The authorization stays in effect until the debt is paid or you cancel it in writing.¹³

Step 4 is the signature. Individuals sign personally; for a business, the person responsible for remitting tax payments signs.

How to Submit It

Fax the completed form to IDOR at 217-785-2635, or mail it to the Installment Contract Unit, PO Box 19035, Springfield, IL 62794-9035. Fax is faster and gives you a transmission confirmation, which is worth having if enforcement is close.¹

You can skip the paper form and request a plan through MyTax Illinois instead. IDOR offers a pre-approved option that gives instant approval if you accept the terms it presents. If those terms don’t fit your budget, you can submit a custom request through MyTax, but that version goes to collections staff for review and takes longer.²

How IDOR Sets Your Terms

IDOR reviews the form for completeness and evaluates the financial information you supplied. If something is missing, they contact you. If the review shows you have the ability to pay in full, they will require that instead of granting a plan.¹

Your monthly payment and the length of the plan are set based on your financial condition, not a fixed schedule.² That is why the EG-13 matters so much on larger balances. Clear documentation of genuine hardship gives you a better shot at terms you can actually sustain.

Interest and Penalties Keep Running

An installment plan is not a freeze. Interest and applicable penalties continue to accrue on the unpaid tax for the whole time you are in the agreement.¹ Illinois uses the federal underpayment rate for interest, applied daily.⁴

Late-payment penalties are tiered. A payment 1 to 30 days late carries a 2% penalty on the amount due. After 31 days, the rate rises to 10%. If IDOR has to open an audit or investigation to uncover the liability, the penalty climbs to 15%.⁴ The practical effect is that a larger down payment and a shorter plan cost less overall. Stretching payments out feels easier month to month, but the total can significantly exceed the original debt.

What Counts as Default

If you default, IDOR can cancel the plan and demand the full unpaid balance immediately. From there, the department can levy your bank account or garnish your wages.¹

Default is more than missing a payment. Your plan also fails if you stop filing required returns or fail to pay current taxes as they come due. IDOR expects full compliance going forward while you pay down the old debt. Falling behind on this quarter’s sales tax while paying off last year’s income tax can end the agreement.

If a payment problem is coming, call IDOR before you miss the due date. Renegotiating terms is easier than recovering from a default.

Mistakes That Delay Approval

The most common problem is an incomplete form: a missing Social Security number, no down payment, or no EG-13 attached when the debt is over $15,000. IDOR will come back to you for the missing pieces, and that exchange can add weeks.

The second is combining individual income tax with other tax types on one CPP-1. Those need separate forms, and filing them together gets the submission bounced back.

The third is filing before all required returns are in. IDOR will not approve a plan until every return is filed. Get the returns done first, then send the CPP-1.

1
Illinois Department of Revenue. CPP-1 Installment Payment Plan Request Instructions
2
Illinois Department of Revenue. Payment Plan
3
Illinois Department of Revenue. CPP-1 Installment Payment Plan Request
4
Illinois Department of Revenue. Pub-103, Penalties and Interest for Illinois Taxes