Pennsylvania Form REV-1630 – Underpayment of Estimated Tax by Individuals (2026)
Last reviewed: 2025-11-11
Use the Pennsylvania Tax Form Calculator Pennsylvania Form REV-1630 – Underpayment of Estimated Tax by Individuals as a stand alone tax form calculator to quickly calculate specific amounts for your 2026 Pennsylvania state tax return. Alternatively, you can use one of our Combined Federal and State Tax Estimators to quickly calculate your salary, tax, and take-home pay.
Form REV-1630 is used by Pennsylvania residents and part-year residents to determine whether they underpaid estimated income tax during the year and, if so, to calculate any interest or penalty. The form compares your actual payments and credits with required quarterly installments, generally based on 90% of current-year tax or 100% of the prior-year liability (safe-harbor rule).
Taxpayers who make estimated payments, have non-withheld income, or receive substantial untaxed income such as self-employment, rental, or investment income should complete this form to verify compliance and avoid additional charges.
How to Complete Form REV-1630
Step 1 – Determine Tax Liability: Enter total PA tax due from your PA-40 (Line 12). Multiply by 90% to find the safe-harbor target.
Step 2 – Report Credits: Include withholding, estimated payments, and refundable credits from Lines 13–23 of your PA-40. Subtract these from your total tax to find any unpaid amount.
Step 3 – Divide Into Installments: The unpaid portion is divided equally across the four quarterly periods. Each period represents an installment date: April 15, June 15, September 15, and January 15 of the following year.
Step 4 – Compare to Payments: Enter the actual payments or withholding per period. Any shortfall represents an underpayment subject to interest unless an exception in Section II applies.
| SECTION I — CALCULATING THE UNDERPAYMENT | ||
| 1a | Tax liability (Line 12 of PA-40) | |
| 1b | 90% of tax liability (1a × 0.90) | |
| 2 | Total credits (lines 13,17,21,22,23 of PA-40) | |
| 3 | Line 1a minus Line 2 | |
| 4 | Line 1b minus Line 2 (base for installments) | |
| LINE 5 – Divide Line 4 by four for equal installments | ||
| 5a | Installment for payment period a | |
| 5b | Installment for payment period b | |
| 5c | Installment for payment period c | |
| 5d | Installment for payment period d | |
| Continue with Columns a-d for: timely payments (Line 6), carryover credits (Line 7), total applied (Line 8), underpayment (Line 9), overpayment (Line 10). Then if any underpayment remains, complete Section II (Exceptions) or Section III (Interest penalty). | ||
Examples and Scenarios
Example 1 – Full Compliance: Chris’s 2025 PA tax liability is $4 000. 90% = $3 600. Chris paid $900 quarterly on time, totaling $3 600, meeting the safe-harbor rule. No penalty applies.
Example 2 – Late or Uneven Payments: Jordan owed $4 800 for 2025 but paid only $600 in April and $1 000 in each later quarter. Because earlier installments were short, interest applies to the underpaid amount for the affected quarters.
Example 3 – Underpayment with Credits: Taylor had $5 000 liability but $3 000 withheld and $1 000 estimated payments. The remaining $1 000 is below the $1 999 de minimis threshold, so no penalty is charged.
Last reviewed: 2025-11-11: If you believe this form requires an update, please contact us.
Further Guidance and Related Forms
- Form PA-40 – Individual Income Tax Return
- Form REV-1630A – Underpayment of Estimated Tax by Individual Farmers
- Pennsylvania Department of Revenue – PIT Forms
Keep records of each estimated payment date and amount, as the Department of Revenue calculates interest daily from the due date of each installment until payment. You can avoid future penalties by paying at least 90 % of current-year tax or 100 % of prior-year liability through timely installments.
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Frequently Asked Questions
What is Form PA-40?
Form PA-40 is the Pennsylvania Individual Income Tax Return used by residents, part-year residents, and nonresidents to report taxable income and claim credits or deductions.
Can I amend to claim a refund?
Yes, if withholding or estimated payments exceeded revised liability.
Does PA tax long-term capital gains?
Yes—PA taxes “net gains from the sale, exchange, or disposition of property.” This wage page doesn’t include capital gains; model them with Schedule D.
What rate does Pennsylvania use?
Pennsylvania has a flat personal income tax rate of 3.07 % for all taxable income.
Where do I enter the exclusion amount?
You do not enter it separately; if fully excluded, you simply omit the gain from your PA-40. Partial exclusions must be shown on Schedule 19.
Important Notes
All calculations are estimates for guidance only. Always review your return and consider professional advice when submitting official filings.