Quarterly Estimated Taxes: The Math Every Freelancer Needs

The first April after going freelance is when people learn, sometimes painfully, that the IRS expects tax payments throughout the year. Four of them. One per quarter. Miss them and you'll owe a penalty on top of the tax itself.

This is the math.

Why freelancers pay taxes four times a year

When you're on a W-2, your employer withholds federal income tax, Social Security, and Medicare from every paycheck and sends it to the IRS. You never see the money. You file in April to settle any difference.

When you're 1099, there's no withholding. The IRS still wants revenue throughout the year — sending it is your job. If you expect to owe more than $1,000 in federal tax after accounting for any withholding (usually zero if you're fully self-employed), you're required to make quarterly estimated payments.

Skip the payments and you'll owe an underpayment penalty. The IRS calculates it based on the federal short-term rate plus 3%, which currently runs around 8% annualized. On a $5,000 underpayment, that's roughly $400 in penalties on top of the tax. Not a huge number, but avoidable.

The self-employment tax calculation

Before calculating your quarterly payment, you need to understand self-employment tax, because it hits before income tax and a lot of first-year freelancers miss it.

When you're W-2, your employer pays half of Social Security and Medicare taxes (7.65%) and you pay the other half via paycheck deductions. Self-employed, you pay both halves: 15.3% of net self-employment income.

The formula with the IRS adjustment built in:

SE tax = net profit × 0.9235 × 0.153

The 0.9235 factor exists because the IRS lets you deduct the employer-equivalent half of SE tax before calculating your SE tax base. You don't have to do anything to get this — just use 0.9235 in the formula.

On $20,000 of quarterly profit: $20,000 × 0.9235 × 0.153 = $2,826 in SE tax. That number exists entirely before income tax.

Adding income tax to the estimate

After SE tax, add your estimated federal income tax. The IRS lets you deduct half your SE tax from income before applying your bracket rate, which slightly lowers the income tax base.

For 2026, the federal income tax brackets for single filers:

| Taxable income | Rate | |---|---| | Up to $11,925 | 10% | | $11,926–$48,475 | 12% | | $48,476–$103,350 | 22% | | $103,351–$197,300 | 24% |

Most freelancers in their first few years land in the 22% bracket. A working rule of thumb: budget 35% of net profit for combined SE tax plus income tax in the 22% bracket, after the deductions that offset things. In the 24% bracket, budget closer to 38%.

These aren't exact. Your final number depends on the standard deduction ($15,000 for single filers in 2026), whether you're deducting self-employed health insurance premiums or retirement contributions, and whatever your state does on top. But 35% is a defensible working estimate when you need something to go on.

The safe harbor rule

This is the rule worth memorizing.

You will not owe any underpayment penalty if your quarterly payments equal at least 100% of your prior year's total federal tax liability, divided evenly across four quarters. If your prior-year adjusted gross income was over $150,000, the threshold rises to 110%.

This is the safe harbor. It's especially useful in your first year of freelancing, when income is unpredictable and estimating future profit feels like guessing.

If you paid $8,000 in total federal tax last year, paying $2,000 per quarter this year keeps you penalty-free — regardless of how much you earn in the current year. Even if you make twice as much and owe $16,000 at filing, the penalty doesn't apply as long as those four payments landed on time.

The tradeoff: you'll owe a lump sum in April, which requires cash planning. But you're insulated from penalties, which matters a lot when income is lumpy.

The 2026 due dates

Quarterly payments don't follow calendar quarters. The IRS runs its own schedule:

| Period | Due date | |---|---| | Q1 (Jan 1 – Mar 31) | April 15, 2026 | | Q2 (Apr 1 – May 31) | June 16, 2026 | | Q3 (Jun 1 – Aug 31) | September 15, 2026 | | Q4 (Sep 1 – Dec 31) | January 15, 2027 |

Q2 covers only two months. That's not a typo. Plan cash flow accordingly.

Miss a due date and the penalty calculation starts from the day you were supposed to pay. Partial payments get partial penalties. Payments made early are fine.

To pay: use IRS Direct Pay at irs.gov (free, no account required) or EFTPS (Electronic Federal Tax Payment System, better for setting up recurring payments). Both are free. Any third-party site charging a fee to process a federal estimated tax payment is charging you unnecessarily.

A working formula

For a single-person freelance setup with no other income complications:

Estimate quarterly net profit (revenue minus deductible business expenses for the quarter)
Calculate SE tax: net profit × 0.9235 × 0.153
Calculate income tax estimate: (net profit − half of SE tax) × your estimated bracket rate
Add SE tax + income tax estimate for your quarterly payment
Compare against safe harbor: if step 4 is less than prior year total federal tax ÷ 4, pay the safe harbor amount instead

Example at $15,000 quarterly net profit, 22% bracket:

SE tax: $15,000 × 0.9235 × 0.153 = $2,120
Half of SE tax (deductible from income): $1,060
Income tax: ($15,000 − $1,060) × 0.22 = $13,940 × 0.22 = $3,067
Quarterly payment: $2,120 + $3,067 = $5,187

State taxes are separate and vary by state. If you're in California, New York, or another high-tax state, run the same logic with your state's bracket and pay separately to your state's revenue authority.

What to do with this

Set aside 35–38% of every invoice payment as it comes in, before you spend any of it. Keep it in a separate savings account if you can. Run this formula once a quarter, send the payment by the due date.

The tracking side is where most people fall behind. The Quarterly Tax Calculator in the 1099 Money System runs this math from your income and expense data, outputs your federal estimate, and surfaces the due dates. If you're already tracking revenue and expenses in the same sheet, the estimate is one formula away.

The single most expensive habit in freelance finances is treating every client payment as take-home pay. Roughly 35 cents of every dollar you invoice belongs to taxes. Separating that money as it arrives is what makes April a non-event.

For informational purposes only. Tax rates, brackets, and rules change annually — confirm current figures with the IRS or a qualified tax professional before filing.