2026 Quarterly Estimated Tax Calculator

Federal estimated tax is a pay-as-you-go method for tax that is not covered through withholding. It can account for expected income tax and additional federal taxes already determined elsewhere, including an entered self-employment-tax amount.

This planner models calendar-year individuals using either regular installments or a supported annualized income workflow. It first estimates total federal tax, tests the general threshold, and compares the available annual-payment targets before applying withholding and payment history.

Estimated payments commonly matter when self-employment income, interest, dividends, gains, rents, or other taxable income has little or no federal withholding. A wage earner can also have a payment gap when projected withholding is too low for the total expected liability.

The ordinary rules do not cover every taxpayer. Farming and fishing, household employment, nonresident status, and fiscal-year tax periods can invoke different calculations or dates.

In the modeled general rule, expected tax after refundable credits is compared with projected federal income tax withholding. When the amount still owed is below $1,000, this calculator indicates that estimated payments are generally not required.

The comparison is strict: an expected balance of exactly $1,000 is not below the threshold. The result is cautious language rather than a claim of universal legal exemption.

The current-year target is 90% of estimated 2026 total federal tax. Refundable credits reduce the modeled total tax, while withholding and estimated payments are payments against that liability and do not reduce the tax itself.

A changing income forecast changes this target when the form is recalculated. TaxArith does not automatically amend future installments or retroactively correct earlier ones.

A full 12-month 2025 return makes a prior-year comparison available. The ordinary amount is 100% of 2025 tax, but the percentage becomes 110% when 2025 AGI is strictly above $150,000 for the supported non-MFS statuses.

Married Filing Separately uses a separate $75,000 threshold. AGI equal to $75,000 or $150,000, as applicable, does not trigger 110%. The planner uses the smaller available current-year or prior-year annual target.

Prior-year tax is the relevant tax shown on the 2025 federal return. It is not the refund, balance due, AGI, withholding, estimated payments, or total payments shown elsewhere on the return.

If the 2025 return did not cover all 12 months, this calculator ignores the visible tax and AGI entries when selecting the target and uses the current-year 90% method alone.

Projected federal income tax withholding for all of 2026 counts toward the required annual payment before an estimated-payment amount is calculated. Enter the full-year projection, not merely withholding received through today.

Social Security and Medicare payroll withholding are not federal income tax withholding and should not be included. The tool does not recommend a new withholding election.

Enter the 2025 overpayment credited to 2026 separately from each estimated payment. The table compares cumulative requirements with cumulative paid amounts, carries an earlier excess forward, and keeps an earlier shortfall visible.

Amount-only entries do not tell TaxArith the actual payment date. A later catch-up may reduce what remains without automatically eliminating a possible penalty for an earlier period.

• Payment 1: January 1, 2026–March 31, 2026, due April 15, 2026.
• Payment 2: April 1, 2026–May 31, 2026, due June 15, 2026.
• Payment 3: June 1, 2026–August 31, 2026, due September 15, 2026.
• Payment 4: September 1, 2026–December 31, 2026, due January 15, 2027.

The January 15 payment generally does not have to be made when the 2026 return is filed by February 1, 2027 and the entire balance due is paid with it. The calculator keeps payment 4 in the schedule and does not automatically apply that exception.

IRS estimated-tax periods have different lengths: three months, two months, three months, and four months. Calling them four equal calendar quarters can hide the unusually short April–May period and the June 15 due date.

The equal amounts shown by the regular method are payment targets; they do not imply four equal time periods.

A safe harbor is a payment benchmark, not final liability. Meeting a target can still leave tax due at filing—for example, paying 90% of current-year tax normally leaves part of a fully accurate projected liability unpaid.

Refund or balance depends on total tax compared with withholding and payments. A projected refund is not guaranteed, and sufficient annual payments can still be late for one or more periods.

A material income, deduction, credit, or other-tax change can alter expected tax and the current-year target. Recalculate with a new full-year projection, but do not treat the new equal schedule as a determination that earlier installments were timely.

Publication 505 includes a separate amended estimated-tax worksheet. This calculator labels a recalculated result as a current planning projection and does not claim to complete Worksheet 2-12.

The regular method assumes income is received relatively evenly and uses cumulative 25%, 50%, 75%, and 100% requirements after standard withholding allocation. Payment history is then applied without hiding an earlier shortfall.

Annualized Income uses cumulative January–March, January–May, January–August, and full-year amounts, the official annualization factors and applicable percentages, and the Worksheet 2-9 regular-installment limitation. It may require Form 2210 and Schedule AI; TaxArith does not calculate penalties or replace those forms.

Self-employment tax is separate from federal income tax, but an already-calculated amount can be part of total federal tax for estimated-payment planning. Use the Self-Employment Tax Calculator, then enter the resulting tax once in Other federal taxes.

Do not enter gross business income or federal income tax in that field. This planner does not calculate Schedule SE or determine which other taxes apply.

Both federal income tax withholding and estimated payments are payments against tax liability. Neither changes the underlying tax; they change how much has been paid toward it and therefore the projected balance or refund.

TaxArith keeps the credited prior-year overpayment and four entered estimated payments separate from withholding. It assigns the amounts to the selected payment rows but does not infer exact payment dates or decide whether any payment was late.

It does not calculate Form 2210 penalties or interest, complete Schedule AI, model amended Worksheet 2-12 installments, or support annualized capital-gain worksheets, self-employment Section B, AMT, foreign-income worksheets, household employment tax, recapture, or every credit.

It also excludes farmer and fisher special rules, fiscal-year taxpayers, nonresident aliens, estates, trusts, corporations, spouse payment allocation, state and local estimated taxes, payment processing, return preparation, and filing. Actual filed results can differ.

Federal estimated-tax rules, payment dates, and Worksheet 2-9 mechanics were verified using the final IRS 2026 Form 1040-ES and Publication 505. The annualized result is a supported planning subset and does not calculate Form 2210 penalties.

The federal income-tax estimate comes from TaxArith's shared versioned 2026 brackets, standard deductions, preferential-rate thresholds, deduction handling, and credit conventions. Tax law, IRS guidance, or personal circumstances can change an appropriate result.