Is This Tax Letter Scary? IRS & CT DRS Letters Explained

Plain-English explanations of the most common Connecticut DRS and IRS letters: what each one means, what to do, and how fast to respond.

For general education only. Not tax, legal, insurance, or investment advice, and not a promise of any result. Tax rules and due dates change, so confirm with the IRS (irs.gov), the CT Department of Revenue Services (portal.ct.gov/DRS) or your town before you act, and ask your tax preparer about your own situation.

How to use this page: find the notice or letter number (IRS letters show it in the top or bottom right corner; most CT DRS letters show a Letter ID in the upper right). Letters marked We can help with this are ones we can help you understand, gather documents for, and prepare a response or payment plan. Letters marked Respond directly need you to answer the agency yourself, or need an enrolled agent, CPA or attorney.

Jump to: Connecticut DRS letters · IRS notices · Scam warning signs

Connecticut DRS letters and notices

CT DRS doesn't publish a public list of notice numbers the way the IRS does, so these are described by the title DRS uses. Most DRS letters can also be viewed in myconneCT under More… > Correspondence > View Letters.

Billing notice (balance due)

We can help with thisCT DRS
What it means
DRS says there's unpaid tax, interest and possibly penalties for a specific tax type and period. The Letter ID is printed in the upper-right corner of most DRS letters.
What to do
Check the period and amount against your records. Pay in myconneCT using the Letter ID, or, if you can't pay in full, request a myconneCT payment plan (2 to 12 months; available when your returns are filed, the balance is $50,000 or less, and the account isn't in collection). If you disagree, contact DRS before the due date.
Deadline
Pay or respond by the due date on the notice. Interest keeps adding up on unpaid tax.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: paying a bill with the Letter ID (myconneCT) · CT DRS: installment agreement requirements

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Underpayment of estimated tax bill (Form CT-2210 interest)

We can help with thisCT DRS
What it means
Your estimated payments or withholding were short for one or more installments, so DRS charged interest at 1% per month (or part of a month) on each short installment. If you don't file Form CT-2210 with your return, DRS calculates the interest and sends a bill.
What to do
Compare the bill to your CT-1040ES payment dates. Form CT-2210 lists the exceptions (such as the prior-year exception); ask your tax preparer whether one applies. Otherwise, pay the bill or set up a payment plan, and raise next year's estimates.
Deadline
By the due date on the bill.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: 2025 Form CT-2210 and instructions · CT DRS: 2026 Form CT-1040ES

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Mathematical error notice (return adjusted)

We can help with thisCT DRS
What it means
DRS corrected your return for an arithmetic error, an entry on the wrong line, or a missing form or schedule, and the tax changed. Under state regulations this is not a deficiency notice, so there's no protest right for the math change itself.
What to do
Read what DRS changed. If it's right, pay the amount by the date on the notice (or note the smaller refund). If it's wrong, send the correcting information, such as a missing schedule or form, by that date.
Deadline
Within the time on the notice.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
Conn. Agencies Regs. § 12-731-1, Mathematical errors · CT DRS: 2025 CT-1040 instructions (designee may answer math-error notices)

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Discrepancy notice from the Income Tax Audit Unit (federal change or mismatch)

We can help with thisCT DRS
What it means
DRS compared your CT return to IRS information (for example, an IRS adjustment) and found a difference. It proposes changes to your Connecticut tax. It's the state version of an IRS CP2000.
What to do
You don't need to file an amended return for the year in the notice; DRS corrects that year. If you disagree, tell DRS in writing why and attach documents. If the same error affects other years, those may need amended returns.
Deadline
By the due date on the notice. If you don't respond, DRS issues a Notice of Assessment and interest keeps adding up. Penalties: 10% for underreporting, or the greater of $50 or 10% for failing to report income.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: Discrepancy program FAQs · CT DRS: Income tax audit programs

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Failure to File Notice (no record of your return)

We can help with thisCT DRS
What it means
DRS's Non-Filer Program believes you had to file a Connecticut income tax return for the year shown and didn't. DRS says some of these letters go to people who weren't required to file.
What to do
If you were required to file, file the return (and pay what's due). If you weren't, check the box on the back of the notice and include the documents it asks for.
Deadline
By the date on the notice. Questions: the Income Tax Audit Unit, 860-541-4542.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: Income tax audit programs (Non-Filer Program)

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Notice of Assessment (including audit assessments)

Respond directlyCT DRS
What it means
A formal assessment of tax, interest and penalty, often after an audit or after a discrepancy notice that went unanswered.
What to do
If you agree, pay or set up a payment plan. If you disagree, you can file a written protest with the DRS Appellate Division (optional Form APL-002). Interest keeps running on unpaid tax during a protest.
Deadline
A protest must be received, or postmarked, within 60 days of the notice date (10 days for a jeopardy assessment).
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: penalty waiver, offer in compromise or protest · CT DRS: Policy Statement 2001(3), Your Rights as a Connecticut Taxpayer

For a formal protest or an audit, consider an enrolled agent, CPA or attorney. If you only need help reading the notice or setting up a payment plan, we can help with that.

Refund Protection Notice (identity verification)

Respond directlyCT DRS
What it means
Something on a return filed under your name triggered DRS's fraud screen, so DRS is holding the refund until it confirms you filed it.
What to do
With the notice in hand, use "Verify your identity" on the DRS Refund Protection Program page and answer a few questions only you should know. If that doesn't work, DRS lists what to send its Fraud Unit (a copy of your ID plus a W-2 or last pay stub).
Deadline
As soon as you can. DRS can't release the refund until you verify. The notice lists DRS's secure toll-free number, 855-842-1441.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: Refund Protection Program · CT DRS: Refund Protection Program FAQs · CT DRS: Refund Protection problems page

Respond directly to CT DRS using the steps on the notice. Only DRS can verify your identity.

Notice of Refund Offset / Notice of Intent to Offset

We can help with thisCT DRS
What it means
Notice of Refund Offset: your CT refund (or part of it) was sent to another agency for a debt, such as child support or a state agency debt. The notice shows the original refund, the amount taken, and the agency's contact details. Notice of Intent to Offset (sent by certified mail): DRS plans to take your federal refund for a past-due CT tax debt.
What to do
For a refund offset, contact the agency named on the notice if you think the debt is wrong. For an intent to offset, pay the debt in full or send DRS evidence that it isn't owed or was paid.
Deadline
Intent to offset: within 60 days of the notice date.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: Treasury Offset Program · CT DRS: Federal Offset Program

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Business notices: sales and use tax or withholding estimated assessment (missing returns)

We can help with thisCT DRS
What it means
If a sales and use tax, withholding or other myconneCT business return wasn't filed, DRS can issue an estimated assessment based on your filing history, tax type, filing frequency and industry. For sales and use tax, the law adds a penalty of 15% of the estimated tax or $50, whichever is greater, plus interest.
What to do
DRS says not to pay the estimated amount. Instead, file the missing return (even if no sales happened in that period) and pay the actual tax due, if any. Then review whether any penalty can be waived.
Deadline
By the protest expiration date shown on the notice.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: myconneCT FAQs (estimated assessments) · CT General Statutes § 12-416 (estimate and assessment if no return made) · CT DRS: sales tax information (returns due even with no sales)

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Pass-through entity tax (PET) notices

We can help with thisCT DRS
What it means
For partnerships and S corporations that elect the CT pass-through entity tax (elective for tax years starting in 2024 or later). The common one is a bill for underpaid PET estimates: DRS calculates interest at 1% per month separately for each installment, so a late quarter can be billed even if later payments covered the year.
What to do
Check the CT-PET ES payment dates (Apr 15, Jun 15, Sep 15 and Jan 15 for calendar-year filers) against what was paid. Pay the bill, or send correcting information if a payment was misapplied. Remember the election can't be changed after it's made.
Deadline
By the due date on the notice.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: Pass-through entity tax information · CT DRS: Form CT-PET ES (due dates, 1% interest) · CT DRS: Worksheet CT-2210PE

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Request for information or documents (for example, a CT EITC review letter)

We can help with thisCT DRS
What it means
DRS needs proof before it finishes processing your return, for example documents supporting a Connecticut Earned Income Tax Credit claim.
What to do
Send exactly what the letter lists. For CT EITC letters, log in to myconneCT, choose "Upload Earned Income Tax Credit (EITC) Documents", enter the Letter ID, upload and submit. Keep the confirmation number.
Deadline
By the date on the letter. Processing (and any refund) waits until DRS has the documents.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
CT DRS: how to upload EITC documents in myconneCT · CT DRS: CT Earned Income Tax Credit

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

Common IRS notices

CP2000 (proposed changes: income doesn't match)

We can help with thisIRS
What it means
Income or payment information the IRS got from employers, banks or others (W-2s, 1099s) doesn't match your return. The notice proposes changes that may raise, lower or not change your tax. It isn't a bill.
What to do
Read the whole notice. Fill out and sign the response form, saying whether you agree or disagree, and include supporting documents. You can reply by the IRS document upload tool, fax or mail. If you agree and have nothing else to report, you don't need to amend.
Deadline
Reply by the date on the notice. If you don't, the IRS may send a bill.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP2000 series notice

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

CP14, CP501 and CP503 (balance due reminders)

We can help with thisIRS
What it means
CP14 is the first notice that there's an unpaid balance. CP501 is a reminder, and CP503 is the second reminder that the balance is still unpaid.
What to do
Check the amount. Pay by the due date, or apply for a payment plan (online payment agreement or Form 9465). If you disagree, call the number on the notice with your records ready.
Deadline
By the due date on the notice. After that, penalties and interest grow, and the next step is a CP504.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP14 notice · IRS: Understanding your CP501 notice · IRS: Understanding your CP503 notice · IRS: Payment plans

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

CP504 (Notice of Intent to Levy)

Respond directlyIRS
What it means
The final reminder before the IRS can levy (take) wages, bank accounts or your state tax refund for an unpaid balance. The IRS may also file a federal tax lien.
What to do
Act right away: pay, or set up a payment plan. If you disagree, call the number on the notice. You can ask for a Collection Appeals Program (CAP) appeal before collection action.
Deadline
Immediately.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP504 notice

Respond directly to the IRS now. For a levy, or if collection has already started, consider an enrolled agent, CPA or attorney.

CP11 and CP12 (math error changes)

We can help with thisIRS
What it means
The IRS corrected one or more mistakes on your return. CP11: the change means you have a balance due. CP12: the change affects your refund (bigger, smaller, or a refund instead of a balance).
What to do
Compare the "what we changed" section with your return. If you agree, pay (CP11) or wait for the refund (CP12), and fix your own copy of the return. If you disagree, contact the IRS at the number on the notice.
Deadline
By the date on the notice.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP11 notice · IRS: Understanding your CP12 notice

We can help with this. We can help you understand the letter, gather documents, and prepare your response or payment plan. Get help (priced by quote).

CP59 (no record of your prior-year return)

We can help with thisIRS
What it means
The IRS has no record that you filed a prior-year personal return.
What to do
File the return right away, or explain why you didn't have to file. If you believe the IRS made a mistake, it lists Form 15103 for that.
Deadline
As soon as possible. Waiting can mean losing a refund or credits, and more penalties and interest if tax is due.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP59 notice

We can help with this. We can help you understand the letter, gather documents, and prepare the missing return or your response. Get help (priced by quote).

CP05 (return under review)

IRS
What it means
The IRS needs more time to verify income, withholding, credits or business income on your return. It doesn't mean you made a mistake.
What to do
If you filed the return, no action is needed. If you didn't file it, someone may have used your information: complete Form 14039, Identity Theft Affidavit.
Deadline
Allow up to 60 days before contacting the IRS.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP05 notice

CP75 (audit of the Earned Income Credit)

Respond directlyIRS
What it means
The IRS is auditing your return and needs documents to verify the Earned Income Credit (and possibly related credits). It's holding those parts of your refund.
What to do
Send copies of the requested documents with the response form, by upload, fax or mail, all at once.
Deadline
By the date on the notice.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP75 notice

This is an audit. Respond directly to the IRS, or consider an enrolled agent, CPA or attorney.

Letter 5071C, Letter 4883C and CP01H (identity and account locks)

Respond directlyIRS
What it means
5071C (part of the CP5071 series) and 4883C: a return was filed under your SSN or ITIN, and the IRS needs you to confirm your identity and the return before processing it. CP01H: the IRS locked your account because an SSN on the return matches someone who died before that tax year.
What to do
5071C: follow the letter; if it offers online verification, start at irs.gov/verifyreturn. 4883C: call the Taxpayer Protection Program number in the letter with the letter, the return and a prior-year return. CP01H: check the SSN, then contact the Social Security Administration to correct its records. If you didn't file a return, say so; you may be a victim of identity theft.
Deadline
Right away. The return isn't processed until you verify.
Don't ignore it
Unanswered letters usually lead to more interest and penalties and a stronger next notice.
Official source
IRS: Understanding your CP5071 series notice (5071C) · IRS: Understanding your letter 4883C · IRS: Understanding your CP01H notice

Respond directly to the IRS (or the SSA for CP01H) using the instructions in the letter. Only you can verify your identity.

Is it real? Scam warning signs

  • Real tax letters come by U.S. mail first. The IRS normally makes first contact by mail. CT DRS says it will never contact you by text message or social media about your personal tax information.
  • Red flags (IRS list): a call, email or text that is unexpected, rushes you, threatens you, asks for personal or financial information, or demands payment now.
  • Fake "Tax Processing Unit" letters claiming to come from a Connecticut county and threatening legal action over federal tax debt have been mailed to residents. The CT Attorney General and DRS called them a scam.
  • "Settle your back taxes" calls: DRS has warned about callers offering reductions or settlements, often from numbers without a Connecticut area code.
  • Verify before you pay. Look up the notice number on irs.gov, sign in to your IRS Online Account or myconneCT to see if the letter is there, or call DRS at 860-297-5962 using the number from the DRS website, not the one in a suspicious letter.

Sources: IRS: How to know it's really the IRS · CT DRS: scammers offering tax assistance (Aug 27, 2025) · CT AG and DRS: fraudulent unpaid tax debt letters

Frequently asked questions

What should I do first when I get a letter from the IRS or CT DRS?

Don't ignore it. Find the notice number or DRS Letter ID, read what it says changed or is due, and note the deadline. Then compare it with your records before you pay or reply.

Is a CP2000 a bill?

No. A CP2000 proposes changes because income reported to the IRS doesn't match your return. You reply by the date on the notice saying whether you agree or disagree, with documents. If you don't reply, the IRS may send a bill.

How long do I have to protest a Connecticut Notice of Assessment?

CT DRS says a written protest must be received, or postmarked, within 60 days of the notice date (10 days for a jeopardy assessment). Interest keeps running on unpaid tax while a protest is pending.

Can I set up a payment plan with CT DRS?

Usually, yes. DRS offers myconneCT payment plans of 2 to 12 months when your returns are filed, the balance is $50,000 or less, and the account isn't in collection, under warrant, bankruptcy or criminal investigation.

Why did CT DRS send me a Refund Protection Notice?

Information on a return filed under your name triggered DRS's identity theft screen. DRS holds the refund until you verify your identity on its Refund Protection Program page or by following the notice.

Should I pay a CT DRS estimated assessment for a missing sales tax return?

DRS says not to pay the estimated amount. File the actual return and pay the actual tax due, if any, by the protest expiration date on the notice.

How can I tell if a tax letter is a scam?

Real IRS and DRS contact usually starts by mail. Be wary of calls, emails or texts that are unexpected, rush or threaten you, ask for personal information or demand payment now. Verify through irs.gov, your IRS Online Account, myconneCT or the DRS phone number on its website.

Can Enhance Finance help with my letter?

For the letters marked "We can help with this," we can help you understand the letter, gather documents, and prepare your response or payment plan. Services are priced by quote. For audits, levies and identity letters, respond directly to the agency or work with an enrolled agent, CPA or attorney.

Sources (Checked November 3, 2026)

For general education only. Not tax, legal, insurance, or investment advice, and not a promise of any result. Tax rules and due dates change, so confirm with the IRS (irs.gov), the CT Department of Revenue Services (portal.ct.gov/DRS) or your town before you act, and ask your tax preparer about your own situation.

Got one of the letters marked "We can help with this"? We can help you understand it and prepare your response or payment plan.

Get helpBook a 15-minute call

Or call (475) 242-7941. Services are priced by quote.

Enhance Finance is a small-business finance practice serving Connecticut.