A letter from IRS ACS Support Stop 5050 means your unpaid tax account has moved into the IRS Automated Collection System, and correspondence for your case is being routed through the Kansas City processing center. It is a collection notice, not a final enforcement action, but the IRS is actively pursuing payment. You need to respond, and the right response depends on how much you owe and what you can afford to pay.
What the Notice Actually Means
The Automated Collection System is the computerized branch of the IRS that handles delinquent accounts through a sequence of notices. Support Stop 5050 is the mail unit inside the Kansas City center that receives payments, forms, and documentation tied to those accounts. Both individual income tax debts from Form 1040 and business liabilities like unpaid payroll taxes on Form 941 run through this office.
Most people first see the Stop 5050 address on a CP503 second reminder or a CP504 notice of intent to levy. The CP504 warns that the IRS may seize your state tax refund or other property if you don’t pay or arrange payment within 30 days.1Internal Revenue Service. Notice CP504 The CP503C notice lists ACS Support Stop 5050, PO Box 219236, Kansas City, MO 64121 as the return address.2Internal Revenue Service. CP503C Notice Your specific notice may direct you to a different PO box at the same center, so always use the address printed on the letter in your hand.
If you ignore these notices, the IRS escalates to Letter LT11 or L-1058, a final notice of intent to levy that also grants the right to a hearing.3Internal Revenue Service. Notice of Intent to Levy and Your Right to a Hearing Once that letter goes out and 30 days pass without a response, the IRS has statutory authority to seize wages, bank accounts, Social Security benefits, and other property.4Office of the Law Revision Counsel. 26 USC 6331 – Levy and Distraint
What It Costs to Wait
Every month the balance sits unpaid, the failure-to-pay penalty adds 0.5% of the outstanding tax, capped at 25% of the original amount.5Office of the Law Revision Counsel. 26 US Code 6651 – Failure to File Tax Return or to Pay Tax After the IRS issues a final notice of intent to levy and 10 days pass, that rate doubles to 1% per month.1Internal Revenue Service. Notice CP504 On a $15,000 debt, that’s $150 per month in penalties alone.
Interest compounds daily on top of the penalties. The IRS sets underpayment rates quarterly. For the first quarter of 2026 the rate is 7%, and for the second quarter it drops to 6%.6Internal Revenue Service. Quarterly Interest Rates A $10,000 tax bill can pass $15,000 within two years if it’s left alone.
There is a separate consequence for larger debts. If your total assessed federal tax debt exceeds $66,000 (the 2026 threshold), the IRS can certify it to the State Department as seriously delinquent, which can lead to denial of a new passport or revocation of the one you have.7Internal Revenue Service. Revocation or Denial of Passport in Cases of Certain Unpaid Taxes Simply having a pending installment agreement request is enough to prevent that certification, which is one of the strongest practical reasons to respond quickly even if you can’t pay in full.
How to Respond Based on What You Can Pay
Every piece of correspondence must include your Social Security Number or Employer Identification Number and the notice number printed in the upper right corner of the letter. Include a copy of the notice itself when you can. Without those identifiers, the processing center has no efficient way to match your response to your account.
If You Can Pay in Full
Pay immediately through IRS Direct Pay, EFTPS, or a check mailed with the payment voucher at the bottom of your notice. Interest stops the day the IRS receives payment, and full payment ends penalty accrual entirely.
If You Need a Payment Plan
If you owe $50,000 or less in combined tax, penalties, and interest, you can usually set up a streamlined installment agreement without providing detailed financials. File Form 9465 or apply online, which is faster and cheaper.8Internal Revenue Service. Form 9465 – Installment Agreement Request As of March 2026, setup fees depend on how you apply and whether payments are automatic:9Internal Revenue Service. Payment Plans Installment Agreements
- Direct debit agreement, applied online: $22
- Direct debit agreement, by phone or mail: $107
- Standard agreement, applied online: $69
- Standard agreement, by phone or mail: $178
- Low-income taxpayers: fee waived for direct debit, or reduced to $43 for standard agreements
If you can clear the balance within 180 days, a short-term plan carries no setup fee. Once an installment agreement is in effect, no levies may be served.10Internal Revenue Service. Interim IRM Procedural Update SBSE-05-0112-0264
If You Owe More or Can’t Afford Monthly Payments
For larger balances, or if your income barely covers necessary expenses, the IRS will ask for Form 433-F, the Collection Information Statement. This is a detailed breakdown of monthly gross income, necessary living expenses, and assets.11Internal Revenue Service. Form 433-F – Collection Information Statement The IRS may follow up with a request for bank statements or pay stubs to verify what you reported. Having them ready speeds things up.
Options When a Standard Payment Plan Doesn’t Fit
Currently Not Collectible Status
If paying anything toward the debt would leave you unable to cover basic living expenses, the IRS can designate the account as currently not collectible. Active collection stops, including levies and garnishment, until your finances improve.12Internal Revenue Service. Temporarily Delay the Collection Process The debt itself doesn’t go away. Penalties and interest keep running, and the IRS may file a federal tax lien to protect its claim. The IRS reviews your finances periodically.
Offer in Compromise
An offer in compromise settles the debt for less than the full amount when the IRS agrees you can’t realistically pay it all. Submit Form 656 with a $205 application fee and an initial payment; low-income taxpayers can have both waived.13Internal Revenue Service. Eligible Taxpayers May Be Able to Resolve Tax Debt Through an Offer in Compromise The IRS evaluates income, expenses, asset equity, and future earning potential. It rejects offers that lowball your actual ability to pay.
Penalty Abatement
With a clean compliance history, you may qualify for first-time penalty abatement, which removes failure-to-file and failure-to-pay penalties for a single tax period. Reasonable cause relief is available when circumstances beyond your control prevented timely payment, like serious illness, a natural disaster, or the inability to obtain records.14Internal Revenue Service. Penalty Relief for Reasonable Cause Abatement doesn’t reduce the tax or interest, but removing the 25% penalty cap can save thousands on a large balance.
Deadlines That Protect Your Rights
If you get a final notice of intent to levy (Letter LT11 or L-1058) or a notice of federal tax lien filing (Letter 3172), you have 30 days from the date on that notice to request a Collection Due Process hearing by filing Form 12153.15Internal Revenue Service. Collection Due Process CDP FAQs A CDP hearing freezes collection activity while the IRS Independent Office of Appeals reviews your case, and you can take the matter to Tax Court if you disagree with the outcome.16Internal Revenue Service. Collection Appeal Rights You can use the hearing to dispute the amount owed, propose a payment plan, request an offer in compromise, or argue for penalty abatement.
Miss the 30-day window and you lose the right to a full CDP hearing and Tax Court review. An “equivalent hearing” may still be available, but the IRS won’t halt collection while it’s pending, and there’s no court appeal after.
The Collection Appeals Program (CAP) is a separate track. It covers a broader set of actions, including lien filings, levies, and the rejection, modification, or termination of an installment agreement, and it generally moves faster.16Internal Revenue Service. Collection Appeal Rights The tradeoff is that a CAP decision can’t be taken to court. If your goal is a workable payment arrangement rather than a legal dispute, CAP is often the practical choice.
Where and How to Send Your Response
Use the address printed on your specific notice. Different ACS notices route to different PO boxes at the Kansas City center, and using the wrong one can delay processing by weeks. The CP503C notice, for example, uses ACS Support Stop 5050, PO Box 219236, Kansas City, MO 64121.2Internal Revenue Service. CP503C Notice
Send everything by certified mail with return receipt. The tracking number and signed delivery confirmation are your proof the IRS received your response on time, which matters if the IRS later says nothing arrived. For overnight delivery by FedEx or UPS, the physical street address is 333 W. Pershing, Kansas City, MO 64108.17Internal Revenue Service. Submission Processing Center Street Addresses for Private Delivery Service PDS If your notice lists a fax number, include a cover sheet with your name, taxpayer ID, and page count.
Processing at Stop 5050 typically takes several weeks, and the window stretches during peak filing season. While your case is under review, the IRS generally holds off on new enforcement actions, though that’s not guaranteed unless you’ve formally triggered a hold through a CDP hearing or a pending installment agreement request. Monitor your account through the online portal at irs.gov to see when your balance or status updates. Respond promptly to any follow-up request from the IRS; delays can restart the collection clock.
If You Need Help
You can authorize a tax professional to deal with the IRS on your behalf by filing Form 2848, Power of Attorney and Declaration of Representative.18Internal Revenue Service. Instructions for Form 2848 Enrolled agents, CPAs, and tax attorneys can represent you fully. Unenrolled preparers face significant limits and generally cannot appear before appeals officers or revenue officers.
If you can’t afford representation and IRS action is causing significant hardship, the Taxpayer Advocate Service is an independent organization within the IRS that can step in. Reach TAS at 877-777-4778.19Internal Revenue Service. What Is the Taxpayer Advocate Service and How Do I Contact Them TAS helps when normal channels haven’t resolved your issue or when you’re about to suffer serious financial harm. Low-income taxpayer clinics funded by federal grants also provide free or low-cost representation for those who qualify.