Delaware Quarterly Taxes: Due Dates, Safe Harbor, and Penalties

Delaware quarterly taxes are the estimated income tax payments the state requires when your withholding won’t cover what you’ll owe at filing. For individuals, that threshold kicks in once you expect to owe more than $800 above withholding, and payments are due in four installments on April 30, June 15, September 15, and January 15.¹ Corporations follow a different, front-loaded schedule tied to Form 1100-T. Miss a payment or come in low, and the state assesses 1.5% per month on the shortfall, so the numbers and dates below are worth getting right from the first installment.

Who Has to Pay

Every Delaware resident and nonresident whose expected tax liability exceeds withholding by more than $800 for the year must file a declaration of estimated income tax.¹ That generally catches people with income the employer doesn’t withhold on: self-employment, rental income, dividends, capital gains, and similar sources. If your only income is a W-2 job with Delaware tax withheld and you don’t expect to owe more than $800 on top of that, you don’t have to make quarterly payments.

Farmers and fishermen have their own rule. If at least two-thirds of your gross income comes from farming or fishing, you can skip the quarterly schedule and either make one estimated payment by January 15 and file the return by April 30, or file the return and pay in full by March 1 and ignore estimated taxes entirely.¹

Corporations face a broader rule. Every domestic or foreign corporation that isn’t specifically exempt must file an annual tentative return and make estimated payments regardless of expected liability, gross income, or taxable income.² A corporation that expects to owe zero still files Form 1100-T. Delaware’s corporate rate is 8.7% of federal taxable income apportioned to the state.³

Due Dates for Individuals

Individual estimated payments are due in four equal installments. For calendar-year taxpayers, those dates are:

April 30 — first installment
June 15 — second installment
September 15 — third installment
January 15 of the following year — fourth installment

You can also pay the full estimated amount with the first declaration in April rather than splitting it across the year. Fiscal-year filers shift to the 30th day of the fourth month and the 15th day of the sixth and ninth months of their fiscal year, plus the 15th day of the first month of the following fiscal year.¹

Due Dates for Corporations

Corporate installments are not equal for most companies. Standard calendar-year corporations pay:

April 15 — 50% of estimated tax liability, filed with the Form 1100-T tentative return
June 15 — 20%
September 15 — 20%
December 15 — 10%

Small corporations, defined as those with aggregate gross receipts and gross income not exceeding $20 million for any two of the three preceding tax years, pay four equal 25% installments on the same dates.² Fiscal-year corporations use the same percentages anchored to the 15th day of their fourth, sixth, ninth, and twelfth months.

The front-loaded schedule trips up businesses used to the federal pattern. A standard corporation budgeting four even payments will come up short on April 15, when half the annual estimate is already due.

Calculating What You Owe

Start with an estimate of your total Delaware taxable income for the year and apply the state’s graduated rates, which run from 0% on the first $2,000 to 6.6% on income above $60,000.⁴ Subtract expected withholding. Divide the remainder into installments. Form 200-ES includes a tax computation worksheet that walks through gross income, deductions, and the rate table to arrive at a quarterly amount.

Safe Harbor

You avoid an underpayment penalty if each installment is paid on time and meets one of two tests: at least 90% of the tax shown on the current year’s return, or an amount based on last year’s taxable income calculated at the current year’s rates.⁵ The second test helps when income is rising, because last year’s income can keep you penalty-free even if this year’s bill ends up higher. Delaware’s safe harbor does not include the higher-income surcharge found in the federal rules, so your state and federal safe-harbor amounts may differ.

Uneven Income

If your income arrives unevenly, such as a large fourth-quarter capital gain or a seasonal business that earns most of its revenue in summer, Delaware’s annualized income installment method calculates each period’s payment based on income actually earned during that period rather than assuming a flat quarter-by-quarter split. It’s reported on Form PIT-UND and can reduce or eliminate underpayment penalties.⁶

Mid-Year Adjustments

When income, deductions, or exemptions change substantially after you’ve begun paying, adjust the remaining installments rather than waiting until April. The Form 200-ES instructions let you recalculate and spread the new amount across the remaining installments. Adjustment deadlines track installment deadlines: a change between April 1 and June 1 adjusts the June 15 payment, between June 1 and September 1 adjusts September 15, and between September 1 and year-end adjusts the January 15 payment.¹

How to File and Pay

Individuals use Form 200-ES. Corporations use Form 1100-T, the Tentative Tax Return, rather than a separate estimated voucher. Electronic payments for both go through the Delaware Taxpayer Portal at tax.delaware.gov.⁷ You can also mail a check or money order payable to the Delaware Division of Revenue with the appropriate form. For mailed payments near a deadline, the postmark date counts as the filing date.

Penalties for Missing or Underpaying

Delaware applies separate charges that can run concurrently, so mixing them up understates the cost of a late payment.

Interest on underpayment or late payment of 0.5% per month, or fraction of a month, running from the original due date until the balance is paid.⁸
Failure-to-pay penalty of 1% per month, capped at 25%, on the net tax liability shown on a timely or late-filed return.⁹
Failure-to-file or failure-to-pay estimated tax penalty of 1.5% per month of the computed payment, assessed in addition to the other penalties and interest.⁹

A taxpayer who misses an estimated payment and then pays late on the annual return can face all three at once: 0.5% interest, 1% failure-to-pay, and 1.5% estimated tax penalty, each per month. For corporate returns filed late, the structure is 5% per month plus 0.5% monthly interest from the original due date, with an additional 1% per month (capped at 25%) for failure to pay the liability shown on a timely-filed return.¹⁰ The estimated tax penalty does not apply if you meet one of the safe harbor thresholds.⁵

Extensions

The Director of Revenue has discretion to grant extensions of time for filing returns and for making estimated payments, including individual installments. The Director sets the terms and may require a bond or security worth up to twice the tax amount involved.¹¹ Relief is discretionary, not automatic.

For corporations, a federal extension to file automatically extends the Delaware filing deadline. An extension to file is not an extension to pay. Interest and penalties still accrue from the original due date on any unpaid balance.¹⁰

Federal Payments Run on a Different Calendar

Delaware quarterly obligations don’t replace federal ones. The IRS requires estimated payments when you expect to owe at least $1,000 after withholding and credits, with federal calendar-year deadlines of April 15, June 15, September 15, and January 15.¹²¹³ Delaware’s first individual installment lands on April 30, two weeks after the federal one, so plan on writing two checks on two different dates in April.

1
Delaware Division of Revenue. Declaration of Estimated Income Tax for Individuals
2
Delaware Code Online. Delaware Code Title 30 Chapter 19 – Corporate Income Tax
3
Division of Revenue – State of Delaware. Filing Corporate Income Tax
4
Division of Revenue – State of Delaware. Tax Rate Changes
5
Delaware Division of Revenue. Delaware Fiduciary Estimated Income Tax Form FID-EST Instructions
6
Delaware Division of Revenue. Delaware Underpayment of Estimated Taxes Form PIT-UND
7
Division of Revenue – State of Delaware. Payment
8
Justia Law. Delaware Code Title 30 Chapter 5 Subchapter III Section 533 – Interest on Underpayment
9
Division of Revenue – State of Delaware. Personal Income Tax FAQs
10
Division of Revenue – State of Delaware. Corporate Income Tax FAQs
11
Delaware Code Online. Delaware Code Title 30 Chapter 5 – Returns and Payment of Tax
12
Internal Revenue Service. Form 1040-ES Estimated Tax for Individuals
13
Internal Revenue Service. Estimated Tax