Estimated Quarterly Tax Calculator: When to Pay and How Much

If you have a W-2 job, your employer withholds taxes from every paycheck and sends them to the IRS throughout the year. If you don't have that automatic withholding — because you're self-employed, freelance, or earning significant investment income — you're expected to pay on your own, four times a year. Fail to do it and you'll owe an underpayment penalty on top of your regular tax bill.

Who Needs to Pay Quarterly Estimated Taxes

You need to make estimated tax payments if you expect to owe at least $1,000 in federal taxes after withholding and credits. This typically applies to:

• Freelancers and independent contractors
• Small business owners and sole proprietors
• Partners in a partnership or S-corp owners
• Investors with significant capital gains or dividends
• Retirees with pension, IRA distribution, or Social Security income not covered by withholding

If you have a W-2 job and a side business, you can sometimes avoid quarterly payments by increasing your W-2 withholding to cover the additional tax. Ask your employer to withhold an extra flat amount per paycheck using Form W-4.

2026 Due Dates

| Payment Period | Due Date | |----------------|----------| | January 1 – March 31 | April 15, 2026 | | April 1 – May 31 | June 16, 2026 | | June 1 – August 31 | September 15, 2026 | | September 1 – December 31 | January 15, 2027 |

Note: If a due date falls on a weekend or federal holiday, it shifts to the next business day.

The Safe Harbor Rule

The safest way to avoid underpayment penalties is to meet the IRS safe harbor threshold:

Option 1: Pay 100% of last year's tax liability in equal installments. If your 2025 federal tax bill was $12,000, pay $3,000 per quarter in 2026 and you're penalty-free — even if you end up owing more.

Option 2: If your 2025 AGI exceeded $150,000, the threshold jumps to 110% of prior year tax liability. On $12,000, that means $13,200 total ($3,300/quarter).

Option 3: Pay 90% of the current year's actual tax liability. This works if you can estimate your income accurately, but is harder in practice.

Most self-employed people use the prior-year safe harbor method. It's simple, predictable, and penalty-proof even if income spikes.

Real Example: Freelancer Earning $120,000

Let's walk through a freelancer who expects to earn $120,000 in net self-employment income in 2026, filing as single.

Self-employment tax calculation:

• SE tax base: $120,000 x 92.35% = $110,820 (you multiply by 92.35% because you deduct half of SE tax from the base)
• SE tax at 15.3%: $16,955
• Deduct half of SE tax from income: $120,000 - $8,478 = $111,522 adjusted income

Federal income tax (approximate, 2026 brackets for single):

• Standard deduction: $15,000
• Taxable income: $111,522 - $15,000 = $96,522
• Estimated federal income tax: ~$17,150

Total federal tax: $16,955 + $17,150 = $34,105

Quarterly payment under 90% current-year method: $34,105 x 90% = $30,695 / 4 = $7,674 per quarter

Quarterly payment under prior-year safe harbor: If 2025 tax liability was $28,000 (income was lower that year): $28,000 / 4 = $7,000 per quarter

Using prior-year safe harbor saves the freelancer $674/quarter in cash flow while eliminating penalty risk.

How to Actually Make Payments

The IRS Direct Pay system at irs.gov is the simplest method. Select "Estimated Tax" and the relevant tax year. You can also mail a check with Form 1040-ES or pay via EFTPS (Electronic Federal Tax Payment System), which allows scheduling future payments.

For state estimated taxes, check your state's department of revenue website. Most states follow similar quarterly schedules, though the exact amounts differ.

What Happens If You Miss a Payment

The underpayment penalty is calculated quarterly at the federal short-term interest rate plus 3 percentage points. In 2025 that rate was around 8%. The penalty applies only to the underpaid amount for each quarter — it's not a flat fine.

Missing one quarter doesn't eliminate your ability to use the prior-year safe harbor for the remaining quarters. Catch up as quickly as possible and document your payment dates.

Self-Employed Deductions That Reduce Your Quarterly Bill

Before calculating quarterly payments, account for key deductions that reduce your net SE income:

• Half of SE tax (deductible above the line)
• Health insurance premiums (if not eligible for employer coverage)
• Retirement contributions: SEP-IRA (up to 25% of net SE income, max $70,000), Solo 401k, or SIMPLE IRA
• Home office, equipment, software, professional fees

A freelancer contributing $15,000 to a SEP-IRA reduces taxable income by $15,000 — saving roughly $5,000 in total taxes and reducing quarterly payments accordingly.

Run the Numbers

Use the CalcMoney Self-Employment Tax Calculator to estimate your full SE tax, income tax, and recommended quarterly payment amounts based on your expected earnings.