Estimated Tax Penalty COVID Refund

What the estimated-tax penalty is

IRC § 6654 imposes an addition to tax on individuals (and § 6655 on corporations) who fail to make sufficient quarterly estimated-tax payments during the year. The penalty is computed quarter-by-quarter using the federal short-term rate plus 3 percentage points, applied to the underpayment for each installment period until paid. Safe harbors under § 6654(d) avoid the penalty: paying at least 90% of the current-year liability, paying 100% of the prior-year liability (110% if prior-year AGI exceeded $150,000), or owing less than $1,000 at filing.

On the transcript, the assessment posts as TC 170 (most common) or TC 176 for additional estimated-tax assessments. The penalty is generally computed and assessed at the time the return is filed, so the 23C date is typically close to the TC 150 return-filing date.

Quarterly installment due dates for individuals are April 15, June 15, September 15, and January 15 of the following year. Notice 2021-21 postponed the April 15, 2021 estimated-tax deadline for some categories but expressly did not postpone Q1 2021 estimates for individual taxpayers — producing a wave of § 6654 assessments tied to that quarter.

How the estimated-tax penalty is calculated

For each quarter, identify the required installment (generally one-quarter of the safe-harbor amount). Subtract actual payments and applicable withholding (treated as paid evenly through the year). Apply the federal short-term rate + 3 points to the underpayment for the days from the installment due date to the earlier of (a) the next installment date or (b) the date the underpayment was paid. Sum across quarters to produce the total § 6654 penalty.

Worked numbers: a self-employed taxpayer with irregular 2020 income who fell short of the safe harbor at all four quarterly installment dates may see four separate underpayment periods producing a combined $1,800 penalty assessed as a single TC 170 line at filing.

Why Kwong v. United States may unlock a refund

IRC § 7508A(d) provides a mandatory extension for filing and payment deadlines in a federally declared disaster area. The Kwong ruling read § 7508A(d) to require automatic suspension across the full COVID-19 period. The argument for estimated-tax penalties is narrower than for failure-to-file or failure-to-pay because § 6654 attaches to quarterly installment dates rather than the return-filing or balance-due date. Nonetheless, the same statutory hook arguably suspends installment-payment deadlines for installments due inside the window.

Practically, this means installments due on dates inside the disaster window (e.g., the April 15, 2020 Q1 2020 installment, or the April 15, 2021 Q1 2021 installment that Notice 2021-21 did not postpone) may be Kwong candidates even when the assessment is for a tax year outside the headline COVID set. The Kwong ruling is being appealed; eligibility is not guaranteed. A protective Form 843 preserves the argument.

Finding the estimated-tax penalty on your IRS account transcript

Pull your IRS account transcript (see our transcript guide). For § 6654, look for:

• TC 170 — estimated-tax penalty assessment.
• TC 176 — additional estimated-tax assessment, often tied to amended returns or audit adjustments.
• TC 171 / TC 177 — abatements.
• The 23C date — usually close to the TC 150 return-filing date because § 6654 is computed at filing.
• TC 670 — payment.

Worked example: a self-employed 2020 filer with quarterly underpayments

Consider a self-employed taxpayer with irregular 2020 income who paid no estimated tax in 2020 and owed $24,000 at filing. The IRS computed § 6654 underpayments for each quarterly installment, producing a TC 170 of $1,800 with a 23C date of June 7, 2021 alongside the TC 150 return assessment. The taxpayer paid the full balance in July 2021.

The 23C date and three of the four underlying installment dates (April 15, 2020; June 15, 2020; September 15, 2020) sit inside the disaster window; the fourth (January 15, 2021) also sits inside. A protective Form 843 referencing IRC § 7508A(d), Kwong v. United States, 179 Fed. Cl. 382 (Nov. 2025), and the TC 170 entry preserves a refund claim of $1,800. The protective claim should also identify each underlying installment date because partial relief may be appropriate if the appeal narrows the ruling to only some installment dates.

Common scenarios where estimated-tax may be refundable

Q1 2021 installment caught by Notice 2021-21 carve-out

Notice 2021-21 postponed the 2020 Form 1040 filing deadline to May 17, 2021 but expressly did not postpone the Q1 2021 estimated-tax installment, which remained due April 15, 2021. § 6654 underpayments tied to that installment are inside the disaster window and may be Kwong candidates.

Sharp income drop disqualified the prior-year safe harbor

Many self-employed taxpayers whose 2020 income dropped sharply found themselves outside the prior-year safe harbor without realizing it. The resulting § 6654 assessment is technically valid under the statute, but the Kwong analysis may apply to the underlying installment dates inside the disaster window.

Audit adjustment triggered an additional § 6654 assessment

An IRS audit that increased your tax liability may also increase the estimated-tax underpayment, generating a TC 176 with a later 23C date. If that 23C date sits inside the disaster window, the additional assessment is a Kwong candidate even when the underlying tax year is outside the headline COVID set.

Filing deadline for estimated-tax refund claims

IRC § 6511 requires the refund claim be filed within 3 years of the original return filing or 2 years from the date the penalty was paid, whichever is later. The § 7508A(d) extension under Kwong may further lengthen the window. Confirm specific dates against your transcript before filing.

How PenaltyBack handles estimated-tax claims

We pull your IRS account transcript, identify each TC 170 and TC 176 assessment inside the disaster window, identify the underlying installment dates, and draft a Form 843 protective claim citing IRC § 7508A(d), Kwong v. United States, 179 Fed. Cl. 382 (Nov. 2025), and the specific assessment dates. We file under our authorized representative status. Our work is no-win, no-fee.

Frequently asked questions about estimated-tax refunds

Estimated-tax payment deadlines were not extended like return filing was. Does Kwong still apply?

The Kwong reading is that § 7508A(d) suspends payment deadlines automatically inside the disaster window, regardless of whether the IRS issued a separate notice. The argument is narrower for estimated tax than for failure-to-file, but the protective claim preserves it.

I qualified for the prior-year safe harbor — why was I assessed?

The IRS may have computed the safe harbor incorrectly or applied the 110% high-AGI rule. Pull your transcript, recompute under § 6654(d), and the protective claim may also pursue a straightforward miscomputation theory in addition to the Kwong argument.

My self-employment income dropped sharply in 2020. Is that relevant?

Yes — the annualized-income installment method under § 6654(d)(2) may have produced a different result. The protective claim can be paired with a recomputation under that method.

What if my Q1 2021 estimated payment was hit with a 2020 penalty?

Q1 2021 was not postponed by Notice 2021-21 for individual taxpayers and was due April 15, 2021 — inside the disaster window. § 6654 penalties tied to that installment are Kwong candidates.

Does the Kwong analysis differ for estimated tax vs failure-to-file?

Yes. The argument is more direct for failure-to-file because § 6651(a)(1) attaches to the return-filing deadline that § 7508A(d) explicitly suspends. § 6654 attaches to quarterly installment dates, which is a narrower hook but still arguably covered.

Related

Kwong v. United States, explained. Failure-to-file vs failure-to-pay. How to read your transcript. Form 843 protective claim wording. The IRS may owe you money from COVID.