Side-Hustle Tax Estimator

About this calculator

Estimate the incremental U.S. federal tax effect of side-hustle profit and explore monthly, quarterly and per-payment planning amounts.

Estimate the incremental federal effect of adding one side hustle to entered W-2 wages. This simplified model supports Single and Head of Household filers. It compares selected federal taxes in a wage-only baseline with the same situation plus business activity. The monthly hero amount divides the nonnegative annual difference by twelve.

How the estimate works

Enter annual gross business income, expenses assumed deductible, and expected W-2 taxable wages (box 1 totals). Select your supported filing status, then separately enter Social Security wages and tips (boxes 3 plus 7) and Medicare wages and tips (box 5). Use your expected full-year amounts across your W-2s, not tax withheld or net pay. Payroll bases may differ from box 1; changing one wage field does not change the others.

Values recalculate in memory. Invalid annual inputs pause results, Copy and Print instead of retaining an outdated estimate. Optional payment or scenario errors pause only that tool. All entered amounts accept plain nonnegative USD decimals with at most two decimal places and a maximum of $10,000,000. Business losses are rejected.

Gross revenue, expenses and business profit

Modeled business profit = gross business income − entered business expenses. Revenue is before expenses; it is not profit. Expenses equal to revenue produce zero profit. The calculator assumes your expense amount is deductible for this model, without checking legal eligibility, capitalization, timing or documentation.

The educational expense checkboxes reveal topics to investigate in IRS guidance. Checking home workspace, business driving, equipment/software, platform fees, professional services or supplies never changes the calculation. Only a manual edit to entered expenses changes the model.

Self-employment-tax methodology and W-2 interaction

For the ordinary nonfarm method, modeled net SE earnings are 92.35% of business profit. If those earnings are below $400, this model has no SE tax. Otherwise, Social Security tax is 12.4% of the smaller of net SE earnings and the unused 2026 wage base. Unused base = max(0, $184,500 − entered Social Security wages/tips). The Medicare component is 2.9% of net SE earnings and is not capped by that wage base.

Wages at or above the wage base leave no Social Security SE component, but do not eliminate Medicare SE tax. Half of regular SE tax reduces modeled adjusted gross income. Additional Medicare Tax is separate and does not enter that half-SE deduction. Optional SE methods, farm and church rules, unreported tips, railroad compensation, multiple businesses, partnerships, S corporations and special exemptions are outside this model.

Federal income-tax methodology

Each scenario subtracts the same 2026 basic standard deduction from modeled adjusted gross income, with taxable income floored at zero. The basic deduction is $16,100 for Single and $24,150 for Head of Household. The side-hustle scenario adds profit and subtracts the deductible half of regular SE tax. Progressive rate schedules apply each rate only to its band of taxable income.

These are the supported federal estimated-tax rate schedules, not the filing tax-table bands. A marginal rate applies to the next layer of taxable income; it is not the effective rate on all income or the overall side-hustle planning ratio. This tool does not present any of those as interchangeable.

Additional Medicare Tax uses a $200,000 threshold for both supported statuses. It applies 0.9% to combined entered Medicare wages and taxable SE earnings above that threshold. The wage-only amount is already in the baseline, so only the increase enters the incremental result.

Planning amounts, payments and expense comparison

Incremental federal impact = side-hustle scenario selected federal taxes − baseline selected federal taxes. Selected taxes are regular federal income tax, regular SE tax and Additional Medicare Tax. Ordinary W-2 payroll taxes are unchanged and omitted in both columns. Annual planning amount = max(0, incremental impact); monthly = annual ÷ 12; quarterly = annual ÷ 4. This does not account for existing withholding.

For “I just got paid,” the denominator is gross annual revenue. The tool multiplies your payment by annual planning amount ÷ annual gross revenue. This spreads the accepted annual model over payments; it does not independently tax an invoice. With zero revenue the ratio is unavailable and no payment estimate is shown. Money remaining still needs to cover expenses and excluded taxes/costs.

Expense impact compares the accepted model with an otherwise identical zero-expense model. Income what-if replaces gross revenue only; entered expenses remain fixed in dollars. A scenario below those expenses is rejected. Neither feature predicts income or recommends spending.

Quarterly planning versus required estimated payments

A quarterly planning amount is a budget allocation, not a required payment. Required estimated payments can depend on expected tax, credits, withholding, prior-year tax, safe-harbor rules and special circumstances that this tool does not collect. Consult the 2026 Form 1040-ES instructions (opens in a new tab). Employees with side income may be able to adjust wage withholding through their employer.

For calendar-year 2026, the general IRS installment dates are April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. These dates refer to tax year 2026, including the last installment in 2027. Weekend/holiday adjustments, disaster relief, special taxpayer rules, uneven income and the early-filing exception can affect payment timing. This page does not select a next required payment or determine whether you must pay.

Worked example — illustrative annual inputs

With Single status, $30,000 revenue, $5,000 expenses and $60,000 in each W-2 wage field, profit is $25,000. Net SE earnings are $23,087.50. Social Security SE tax is $2,862.85 and Medicare SE tax is $669.5375, for $3,532.3875 regular SE tax. The half-SE deduction is $1,766.19375.

Baseline taxable income is $43,900 and baseline income tax is $5,020. Side-hustle taxable income is $67,133.80625, with income tax $9,481.437375. Additional Medicare Tax is zero here. Incremental impact is $7,993.824875: $666.15 monthly or $1,998.46 quarterly when displayed to cents. Profit after modeled federal impact is $17,006.18. These are the Reset example inputs, not suggested earnings or deductions.

Frequently asked questions (FAQ)

How much should I set aside for side-hustle taxes?

The monthly figure is one-twelfth of the nonnegative modeled additional federal tax. It is a planning amount under the exclusions shown, not a universal savings percentage or payment instruction.

Is the 15.3% self-employment rate applied to revenue?

No. Expenses first reduce revenue to profit, then the normal net-earnings adjustment and threshold apply. The Social Security component also depends on wages and its annual cap; Medicare is calculated separately.

Why do I enter three different W-2 wage amounts?

Box 1 supplies the income-tax context, boxes 3 plus 7 consume the Social Security base, and box 5 supplies Medicare wages. Payroll exclusions can make these totals differ. Enter full-year totals, not withholding.

What if my wages already reach the Social Security wage base?

The regular Social Security SE component becomes zero. Medicare SE tax can still apply, and Additional Medicare Tax may apply depending on combined Medicare wages and SE earnings.

Does this estimate include QBI or dependents’ credits?

No. QBI and all tax credits are excluded, as are AMT, state/local taxes and the other adjustments listed above. Those exclusions may materially change the actual tax effect.

Is the quarterly amount my required IRS payment?

No. The model divides the annual planning amount by four. It does not collect withholding, prior-year tax or the other information needed for required estimated payments or safe-harbor calculations.

Can I use the per-payment tool for a new invoice?

It applies the accepted annual revenue-based planning ratio to an entered payment. It neither adds that payment to annual revenue nor calculates a separate invoice tax. Zero annual revenue gives no per-payment estimate.

Do expense-topic selections claim a deduction?

No. They only reveal educational guidance. They do not assess eligibility or affect results. The engine uses only the annual expense amount you enter manually.

How do income what-if scenarios treat my costs?

Entered business expenses are held fixed in dollars while revenue changes. The same tax engine, wages and filing status apply. Scenarios with expenses greater than revenue are outside the supported no-loss model.

Will the calculator update itself for a later tax year?

No. It uses the tax year disclosed in Tax rules & sources. A future year requires a reviewed rules update and new tests. Nothing is committed to storage; Reset returns to the documented example, and Copy and Print require your action.