2027 Quarterly Estimated Tax Calculator (Safe Harbor)
To avoid the IRS underpayment penalty, pay quarterly estimated tax by April 15, June 15, Sep 15, and Jan 15. Safe harbor: pay 90% of current year OR 100%/110% of prior year (110% if AGI > $150k). Source: irs.gov Form 1040-ES.
IRS Safe Harbor Rules — Avoid Underpayment Penalty
Three safe harbor paths: (1) Pay 100% of prior year's tax (if AGI ≤ $150k) — 110% if AGI > $150k. (2) Pay 90% of current year's actual tax. (3) Owe less than $1,000 total at filing. Any one path avoids penalty. Most taxpayers use #1 because prior year is known and certain. Source: IRS Form 1040-ES instructions.
Quarterly Deadlines 2027
Q1: April 15, 2027 (covers Jan-Mar income). Q2: June 15, 2027 (covers Apr-May). Q3: Sept 15, 2027 (covers Jun-Aug). Q4: Jan 15, 2028 (covers Sep-Dec). Note Q2 is shorter (2 months) and Q4 is in following calendar year. Pay via IRS Direct Pay, EFTPS, or mail Form 1040-ES voucher.
Who Must Pay Quarterly Estimates
Anyone expecting to owe ≥$1,000 in federal tax after withholding. Common: self-employed, freelancers, gig workers, landlords with rental income, investors with capital gains, S-corp owners receiving distributions. W-2 employees with adequate withholding typically don't need to pay quarterly.
Withholding vs Estimated Tax — Tax Treatment Differs
Withholding is treated as paid evenly throughout the year (no penalty for timing). Estimated tax payments must be made by deadlines or trigger period-by-period penalty calculation. Strategy for end-of-year income spikes: increase W-2 withholding (Form W-4) instead of cutting a large Q4 estimated payment — avoids the period-by-period penalty calc.