Tax tools that show where the numbers come from.

What you owe, and when

• 01 Self-Employment Tax Calculator Your SECA tax on Schedule C profit — Social Security, Medicare, the additional 0.9%, and the deductible half. Open →
• 02 Quarterly Tax Calculator What to send with each 1040-ES, using the safe harbor rules or the annualized method — federal and state. Open →
• 07 Tax Set-Aside Calculator The percentage of each payment to put away for 2026 — worked out for your income, because it runs from 14% to 31%. Open →
• 21 Underpayment Penalty What missing an estimated tax date actually costs — the §6654 charge, worked out over the days and the rate of each quarter. Open →
• 22 Premium Tax Credit The Marketplace subsidy on Form 8962 — the benchmark plan, your share of it, and the 400% ceiling that came back this year. Open →
• 20 Annualized Income Installment Four payments sized to what you had actually earned by each date — for a year that started slow and finished strong. Open →

What you deduct

• 04 Mileage Deduction Calculator Standard mileage for business, medical and charity use — or a reimbursement at your employer's rate, which is a different question. Open →
• 05 Home Office Deduction Calculator Simplified against the regular method on Form 8829 — and the exclusive-use test that decides whether either applies. Open →
• 11 QBI Deduction Calculator The 20% deduction on business profit for 2026 — and the income threshold where a freelancer with no employees can lose it entirely. Open →
• 13 Health Insurance Deduction Calculator How much of your own health insurance premium is deductible on Form 7206 — and how a retirement contribution competes for the same profit. Open →

How you are paid and set up

• 03 1099 vs W-2 Calculator Compare take-home on the same gross — including the employer's half of payroll tax that most comparisons leave out. Open →
• 12 S-Corp vs LLC Tax Calculator When electing S-corp status pays for itself, and when it costs more than it saves — including the payroll you have to run. Open →
• 14 1099 Withholding Calculator Whether a client withholds tax at all, and what the 24% backup withholding takes out when no TIN was given. Open →

Your state

• 08 Maryland Local Tax Calculator All 24 counties and Baltimore City, including Anne Arundel and Frederick — where one dollar of profit can move the rate on everything. Open →
• 09 Indiana County Tax Calculator All 92 counties at one flat rate each, plus Boone — which does not charge a round figure in 2026 and is handled here rather than rounded away. Open →
• 10 New York State Tax Calculator The 2026 rate schedule from Tax Law § 601(vii), and the recapture New York adds above $107,650 — worked out from the IT-201 worksheet. Open →

Retirement plans

• 06 SEP IRA Contribution Calculator How much you can contribute for 2026 — and how a 401(k), a Roth, or health insurance premiums change the answer. Open →
• 15 Solo 401(k) Calculator The highest ceiling of any freelancer plan for 2026 — and the worksheet where the deferral and the business contribution share it. Open →
• 16 SEP vs Solo 401(k) Calculator Both retirement plans on the same profit — and the two cases where the smaller one is the right choice. Open →
• 17 SIMPLE IRA Calculator What a SIMPLE allows, why its $17,000 deferral sits inside the $24,500 ceiling, and where it beats a SEP. Open →
• 18 Retirement Plan Comparison All three plans on your profit, ranked — with the two crossover points where the best plan changes. Open →
• 19 Defined Benefit Calculator The plan capped at $290,000 a year instead of $72,000 — what it can promise, and why the contribution needs an actuary. Open →