Quarterly Tax Calculator

The IRS Form 1040-ES worksheet walks through five steps that our quarterly tax calculator runs automatically.

• Step 1: estimate full-year self-employment net income (gross minus business expenses, Schedule C Line 31).
• Step 2: compute self-employment tax = net SE income × 0.9235 × 15.3%.
• Step 3: deduct half of SE tax above-the-line to get adjusted gross income (AGI = net SE + other income − half SE tax).
• Step 4: subtract the standard deduction (2026: single $15,000, MFJ $30,000, HOH $22,500) to get taxable income.
• Step 5: apply the 2026 federal income tax brackets — 10% on first $11,925, 12% to $48,475, 22% to $103,350, 24% to $197,300, then 32%/35%/37% — to get federal income tax.

Total annual tax = SE tax + federal income tax. Divide by 4 for quarterly payments.

Our quarterly tax calculator runs this end-to-end and shows each step so you can verify against IRS Form 1040-ES.

Tax year 2026 federal income tax brackets (single filer):

• 10% on income up to $11,925
• 12% from $11,925 to $48,475
• 22% from $48,475 to $103,350
• 24% from $103,350 to $197,300
• 32% from $197,300 to $250,525
• 35% from $250,525 to $626,350
• and 37% above

MFJ brackets are double the single thresholds up to the 35% bracket. Standard deduction 2026: single $15,000, MFJ $30,000, HOH $22,500, MFS $15,000.

Self-employment tax is unchanged at 15.3% (12.4% Social Security up to the $176,100 wage base + 2.9% Medicare with no cap, plus 0.9% Additional Medicare Tax above $200K single / $250K MFJ). Social Security wage base rises ~3% per year — for 2026 it's approximately $176,100.

Our quarterly tax calculator 2026 incorporates these brackets and rates so the quarterly payment matches what IRS Direct Pay expects.

Self-employment tax catches many first-time freelancers off-guard because it's separate from federal income tax — and it's 15.3% of net SE earnings BEFORE the income tax brackets kick in.

Mechanics: SE tax = net SE income × 0.9235 × 15.3%. The 0.9235 multiplier represents the employer-share offset (employers pay half of FICA for W-2 employees; self-employed pay both halves but get to deduct the employer half from the SE tax base).

SE tax breaks down as:

• 12.4% Social Security on first $176,100 of net SE income (2026 wage base)
• 2.9% Medicare on all net SE income

Add 0.9% Additional Medicare Tax above $200K single / $250K MFJ. Half of total SE tax is deductible above-the-line — this reduces AGI but doesn't reduce SE tax itself.

Our self employment quarterly tax calculator computes SE tax separately so you can see how it stacks with federal income tax in each quarterly payment.

Tax year 2026 quarterly deadlines and the period each payment covers.

• Q1 — due April 15, 2026, covers income earned January 1 to March 31 (3 months).
• Q2 — due June 15, 2026, covers income earned April 1 to May 31 (2 months — note this is shorter than the others).
• Q3 — due September 15, 2026, covers income earned June 1 to August 31 (3 months).
• Q4 — due January 15, 2027, covers income earned September 1 to December 31 (4 months).

The irregular Q2 length is a long-standing IRS quirk dating to mid-20th century scheduling. If a deadline falls on a Saturday, Sunday, or federal holiday, it shifts to the next business day.

Pay via IRS Direct Pay (free, instant confirmation), EFTPS (business accounts), check with Form 1040-ES voucher, or credit card via approved third-party processor (small fee). Late payments accrue underpayment penalty at federal short-term rate + 3% — about 8% annualized in 2026.

The IRS underpayment penalty applies if you didn't pay enough tax during the year through withholding or quarterly estimates. Safe harbor: pay either of the following to avoid penalty.

• (1) 90% of current-year tax — works if you can accurately project current income.
• (2) 100% of prior-year total tax — increased to 110% if your prior-year AGI exceeded $150,000 ($75,000 if married filing separately).

Most freelancers use the 100/110% rule because prior-year tax is a known number from your filed return. Strategy: divide prior-year tax by 4 and pay that each quarter regardless of how this year trends.

If income drops mid-year, you've over-paid (refund at filing). If income rises sharply, you've under-paid the 90%-current-year test but still hit the safe harbor floor — no penalty.

Our safe harbor tax calculator shows both the 100%-prior-year and 110%-prior-year floors so you can pick whichever applies and compare against the current-year projection.

The even-quarters method (default) assumes income is steady — divide annual tax by 4. The annualized income installment method (AIIM, computed on Form 2210 Schedule AI) computes each quarter's required payment based on income actually earned through that point in the year.

Why use AIIM: if income is lumpy or seasonal, the even-quarters method forces you to pre-pay tax on income you haven't earned yet.

Examples where AIIM helps:

• a tax preparer whose income peaks Jan-April
• a wedding photographer with most bookings May-October
• a retailer whose income arrives in Q4 holiday shopping

AIIM mechanics: at each quarter, annualize YTD income to a full-year estimate, compute hypothetical full-year tax, multiply by the cumulative percentage owed (22.5% by Q1, 45% by Q2, 67.5% by Q3, 90% by Q4), subtract prior payments. The downside: more bookkeeping.

Our quarterly tax calculator defaults to even quarters; for AIIM, manually compute YTD income × cumulative percentage in each quarter.

Tax treatment of your business entity drives how quarterly taxes work.

• Sole proprietor / single-member LLC (disregarded): all net profit flows to your 1040 Schedule C; SE tax applies to net profit; quarterly estimated tax required. Our quarterly tax calculator for LLC handles this directly.
• Multi-member LLC / general partnership: each partner pays SE tax on their share of partnership ordinary income plus guaranteed payments; K-1 reports the partner's share; quarterly required on partner-level income.
• LLC electing S-corp tax treatment: owner-employees take reasonable W-2 salary (subject to FICA via W-2 withholding) plus K-1 distributions (no SE tax on distributions); quarterly estimated tax usually only needed on the K-1 distribution portion, plus federal income tax on the combined income above what W-2 withholding covers.
• C-corp owners pay quarterly only on dividends and salary excess; the corporation pays its own quarterly tax (Form 1120-W).

For most freelancers and small business owners, sole prop or single-member LLC is the default and our quarterly tax calculator applies directly.

1099-NEC and 1099-K income is fully taxable for both federal income tax (10-37%) and self-employment tax (15.3%) — and platforms generally don't withhold any tax. This creates the most common surprise tax bill for new freelancers.

Platforms that generate 1099 income subject to quarterly taxes:

• Uber, Lyft, DoorDash, Instacart, Grubhub, Amazon Flex (rideshare/delivery)
• Upwork, Fiverr, Toptal (freelance services)
• Etsy, eBay, Mercari, Amazon Marketplace (e-commerce)
• Twitch, YouTube, OnlyFans, Substack, Patreon (creators)
• Airbnb, VRBO (short-term rentals — note rental income is usually NOT SE income unless services are provided)

The IRS expanded 1099-K reporting thresholds: $20,000+ and 200 transactions in 2023, $5,000 in 2024, $2,500 in 2025, $600 in 2026. More gig workers will receive 1099s and face quarterly obligations.

Our gig worker tax calculator handles the 1099 case directly — enter total 1099 income as net SE income (or subtract documented business expenses first).

41 states have personal income tax and require quarterly estimated payments parallel to federal. Nine states have no income tax (AK, FL, NV, NH, SD, TN, TX, WA, WY) and require no state quarterly payments. New Hampshire and Tennessee tax dividend/interest income only (no SE tax requirement).

The other 41 states have varying systems:

• most match federal deadlines (April 15, June 15, Sept 15, Jan 15)
• California uses a front-loaded schedule (Q1 30%, Q2 40%, Q3 0%, Q4 30%)
• New York and several northeast states issue separate IT-2105 forms

Each state has its own form: NY IT-2105, CA Form 540-ES, IL Form IL-1040-ES, etc. State tax penalty rates are typically 5-8% annualized.

Our quarterly tax calculator includes an optional state effective tax rate input that adds estimated state tax to each quarterly payment — for precise state amounts, check your state department of revenue website.

Rule of thumb: set aside 25-30% of every gross freelance payment received into a separate tax savings account.

Why 25-30%: a typical freelancer with $80K net SE income owes roughly $11K SE tax + $8K federal income tax = $19K total federal (24% of net). Add 5-7% state tax (varies by state) and the total runs 25-32% of net income. For very low income (< $30K) the rate drops to ~18-22%; for high income ($200K+) it climbs to ~35-40%.

Mechanics: at each freelance payment received, move 25-30% to the tax savings account same day. By quarterly deadline, the savings account holds exactly the quarterly payment amount. This eliminates the most common quarterly tax failure mode: spending the gross payment and having no cash to fund the quarterly deadline.

Our quarterly tax calculator's effective rate output (total tax ÷ gross income) gives the exact set-aside percentage personalized to your income.

The US 1040-ES quarterly system has analogs in other English-speaking tax jurisdictions, with key differences.

• United Kingdom (HMRC Self Assessment): self-employed individuals owing >£1,000 income tax make two 'payments on account' due January 31 and July 31, each equal to half of prior-year tax. Concept matches our US 100%-prior-year safe harbor but with 2 payments instead of 4.
• Canada (CRA quarterly instalments): required when net tax owing exceeded $3,000 federal+provincial (or $1,800 Quebec) in both current and one of two prior years. Deadlines: March 15, June 15, September 15, December 15. CRA suggests three calculation methods: no-calculation, prior-year, or current-year. Self-employed Canadians also pay CPP contributions via instalments.
• Australia (ATO PAYG instalments): required when prior-year tax exceeded A$500. Deadlines: 28 July, 28 October, 28 February, 28 April. ATO calculates suggested instalment based on prior return — taxpayer can override with the instalment-rate method.

Our quarterly tax calculator's math (project annual tax → divide by quarterly count → apply safe harbor) transfers conceptually to all three jurisdictions.

• Mistake 1: not paying quarterlies at all. Triggers underpayment penalty + interest at filing. Fix: even if income is uncertain, pay 100% of prior-year tax ÷ 4 to hit safe harbor.
• Mistake 2: forgetting state quarterlies. Federal-only payments still trigger state penalty in 41 states with income tax. Fix: compute state effective rate and add to quarterly payment.
• Mistake 3: paying SE tax late. SE tax has no withholding mechanism — it's entirely on you. Fix: SE tax is roughly 14.1% of net SE income (15.3% × 0.9235), set aside that much separately from federal income tax savings.
• Mistake 4: using the wrong safe harbor. 100% of prior-year applies only if prior-year AGI ≤ $150K; above that it's 110%. Fix: check prior-year AGI before relying on the safe harbor.
• Mistake 5: skipping Q4. Q4 has the longest cushion (Sept-Jan) but missing it is the most common failure. Fix: calendar all four quarterly deadlines at year start.
• Mistake 6: assuming W-2 withholding covers side income. Side income usually pushes you into a higher bracket. Fix: use Form W-4 Step 4c to add extra W-2 withholding for the side income, OR pay quarterly on the gig income portion.