Quarterly estimated taxes are where landlords get ambushed every April. This planner estimates your year's tax bill in plain English, splits it into four quarterly payments, and shows you the safe-harbor rule that makes underpayment penalties mathematically impossible.
Tell it your income. Rental profit, other income, filing status, deductions. Thirty seconds.
Read the bill. See exactly how the brackets slice your income — and what each quarter costs.
Pay the safe number. The planner picks the quarterly amount that keeps penalties off your back.
Everything stays in your browser. Nothing is sent anywhere.
How the 2026 federal brackets slice your taxable income — one layer at a time.
| Bracket | Taxed at | Income in layer | Tax |
|---|
The rule that lets you sleep. Read it once, use it forever.
The IRS charges an underpayment penalty when you pay too little, too late. But there is a harbor: pay 100% of last year's total tax in four equal, on-time quarterly payments — 110% if last year's AGI topped $150k — and you owe zero penalty, even if this year's actual bill comes in higher. The harbor cares about last year's number, not this year's.
Enter last year's total federal tax above and the planner will compute your safe-harbor quarterly — then recommend whichever number is higher: the estimate, or the harbor.
2026 tax year. Mark them paid as you go — it remembers.
Drag it. Watch the marginal dollar do its damage.
Name it, keep it. Compare this year against next year's plan.