2024 brackets · SE tax · safe harbor · all 50 states

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//// Tax · Quarterly Payments

Quarterly Tax Planner — Full Year View

Plan all 4 estimated tax quarters at once. Per-quarter income and expenses, YTD cumulative tax, safe harbor minimums, underpayment risk flags, and a recommended payment schedule.

401(k) Limit 2024$23,000(+$7,500 catch-up 50+)

Roth IRA Limit$7,000(MAGI phase-out applies)

S&P 500 Avg Return~10%/yr(nominal, historical)

Annual Settings

Filing status

State income tax rate

Planned retirement contributions (annual)SEP-IRA or Solo 401(k) — reduces AGI

Prior year total tax (for safe harbor)From last year's Form 1040 line 24. Leave 0 to use current year estimate.

Q1 (Jan–Mar)

Due Apr 15, 2025

Estimated income

Business expenses

Payment already madeEstimated tax paid this quarter

Q2 (Apr–May)

Due Jun 16, 2025

Estimated income

Business expenses

Payment already madeEstimated tax paid this quarter

Q3 (Jun–Aug)

Due Sep 15, 2025

Estimated income

Business expenses

Payment already madeEstimated tax paid this quarter

Q4 (Sep–Dec)

Due Jan 15, 2026

Estimated income

Business expenses

Payment already madeEstimated tax paid this quarter

Quarterly Payment Schedule

Quarter	Due Date	Net Income	YTD Tax	Recommended Payment	Balance Risk
Q1 (Jan–Mar)	Apr 15, 2025	$22,000	$4,892	$6,345	Risk
Q2 (Apr–May)	Jun 16, 2025	$25,000	$10,774	$6,345	Risk
Q3 (Jun–Aug)	Sep 15, 2025	$26,500	$18,057	$9,028	Risk
Q4 (Sep–Dec)	Jan 15, 2026	$23,500	$25,379	$25,379	Risk

Annual net income

$97,000

after business expenses

SE tax

$13,706

15.3% on 92.35% of net

Total tax liability

$25,379

26.2% effective rate

Recommended payments

$47,097

across all 4 quarters

One or more quarters show payments below the safe harbor threshold. The IRS charges an underpayment penalty of approximately 8% APR on the shortfall (2024 rate). Increase payments to avoid it.

Annual net SE income

annualNet = sum(quarterIncome) − sum(quarterExpenses)

Q1 + Q2 + Q3 + Q4 net

= $97,000

Business income minus deductible expenses, before SE tax deduction

Self-employment tax (15.3%)

seTax = (netIncome × 0.9235) × 15.3%

= ($97,000 × 0.9235) × 0.153

= $13,706

Covers both employee and employer halves of Social Security + Medicare

IRC §1401; SS rate 12.4% on first $168,600, Medicare 2.9% unlimited

Half SE tax deduction

halfSEDeduction = seTax ÷ 2

= $13,706 ÷ 2

= −$6,853 (above-the-line deduction)

IRC §164(f) — reduces AGI, lowering income tax

Federal income tax (2024 brackets)

federalTax = f(AGI, filingStatus, standardDeduction)

Filing: Single

= $11,673

Rev. Proc. 2023-34 — 2024 inflation-adjusted tax brackets

Total annual tax liability

totalTax = seTax + federalTax + stateTax

= $13,706 + $11,673 + $0

= $25,379 (26.2% effective rate)

Q4 safe harbor minimum

safeHarbor = priorYearTax ÷ 4 (or current-year estimate if no prior tax entered)

= $25,379 ÷ 4 (estimated)

= $6,345/quarter

Pay at least this per quarter to avoid underpayment penalty (110% rule applies if prior AGI > $150k)

IRS Publication 505; IRC §6654

Recommended total payments

recommendedTotal = max(safeHarbor × 4, annualTotalTax)

= max($25,379, $25,379)

= $47,097

Key insight

The safe harbor rule lets you avoid underpayment penalties entirely — pay 100% of last year's tax liability (110% if prior AGI exceeded $150k) split across 4 quarters, regardless of actual current-year income.

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