Quarterly Tax Calculator 2026 — Idaho
Self-employed workers in Idaho must make quarterly estimated payments to both the IRS and the Idaho tax authority — missing either can result in underpayment penalties. This calculator shows your combined quarterly estimated tax obligations in Idaho and how much to set aside each month.
Also see: Idaho Self-Employed Tax Calculator →
Expected Income This Year
Your expected gross revenue for 2026
Deductible expenses reduce your taxable income
Your 2026 Quarterly Payments
$4,508
Due April 15, 2026
$4,508
Due June 16, 2026
$4,508
Due September 15, 2026
$4,508
Due January 15, 2027
How It's Calculated
Safe Harbor Rule
To avoid IRS underpayment penalties, pay at least 90% of this year's tax OR 100% of last year's tax liability (110% if last year's AGI exceeded $150,000), whichever is smaller.
90% of this year's tax
$4,057/qtr
Enter 2025 liability above for prior-year safe harbor
How to Pay Quarterly Taxes
Pay online at IRS.gov/DirectPay or via EFTPS (Electronic Federal Tax Payment System). Most states accept payment through their official tax portals. Mail payments with Form 1040-ES.
Frequently Asked Questions
Does my state have quarterly estimated tax payments too?
Most states with an income tax require quarterly estimated payments on self-employment income, similar to federal requirements. Thresholds and due dates vary by state — some states use the same due dates as federal, others differ slightly. Generally, if you owe more than $500–$1,000 in state tax for the year, you'll need to make quarterly state payments as well. Check your state's Department of Revenue website for exact thresholds and due dates.
What is the underpayment penalty rate for 2026?
The IRS underpayment penalty rate for 2026 is the federal short-term rate plus 3 percentage points — typically 7–8% annualized on the underpaid amount. The penalty is calculated quarterly and applied proportionally to how long the underpayment existed. To avoid it entirely, meet the safe harbor: pay 90% of this year's tax or 100% (110% if AGI > $150,000) of last year's total tax liability, in equal quarterly installments.
Idaho Taxes — Frequently Asked Questions
Does Idaho have state income tax in 2026?
Yes. Idaho applies a flat 5.8% state income tax. On a $70,000 salary that works out to $4,060 in state tax for 2026, on top of $6,772 federal income tax and $5,355 FICA.
How much is $70,000 after taxes in Idaho?
A single filer earning $70,000 in Idaho takes home approximately $53,813 per year — about $4,484/month or $2,070 per biweekly paycheck. Total taxes: $16,187 (23.12% effective rate), split between federal income tax ($6,772), FICA ($5,355), and Idaho state tax ($4,060).
How much is $90,000 after taxes in Idaho?
On a $90,000 salary in Idaho, a single filer keeps approximately $66,723 per year ($5,560/month). The overall effective tax rate is 25.86%, of which $5,220 is Idaho state income tax.
What is the Idaho state tax on a $45,000 salary?
Approximately $2,610 for 2026 (single filer). Combined with $3,230 federal income tax and $3,443 FICA, total deductions reach $9,282 and take-home pay is $35,718.
What percentage of my paycheck goes to taxes in Idaho?
Between 20.63% and 25.86% for salaries in the $45,000–$90,000 range (single filer, 2026 rates). The biggest pieces are federal income tax and 7.65% FICA; Idaho state tax adds roughly 5.8% at $70,000. Use the quarterly tax calculator above for your exact numbers.