Quarterly Estimated Tax Calculator.
Calculate your federal + state estimated taxes for the year and per quarter. For sole props, partnerships, S-Corps, and self-employed.
A clean handoff, in four steps.
Everything below is included. Pick your tier on Pricing.
Federal estimates.
Based on AGI + entity type
All 50 states.
Where applicable
Quarterly breakdown.
Apr 15, Jun 15, Sep 15, Jan 15
Safe harbor.
Calculated automatically
Common questions.
Who is this for?
Solo founders, multi-entity owners, and the partners (attorneys, CPAs, bookkeepers) who serve them.
What does this cost?
See Pricing. Most customers choose the Compliance Subscription which includes everything tracked, every state, every deadline.
Is there a setup fee?
No. You pay only the state fee plus our flat service fee. Cancel anytime.
How fast can I start?
Most filings start within an hour of payment. State turnaround varies by jurisdiction.
What if I need help?
Our specialist team is on email, chat, and phone. BosAI answers most questions instantly.
Quarterly Estimated Taxes, step by step.
Enter income.
Estimated annual income
Enter entity type.
Sole prop, partnership, S-Corp, LLC
See federal + state quarterly.
4 due dates with exact amounts
Set reminders.
Compliance Subscription sends alerts
Three reasons it works.
Federal + state
Both calculated
Safe-harbor automatic
Avoid underpayment penalty
Entity-aware
Different rules per entity type
Real use cases.
Self-employed
Quarterly estimates throughout the year
S-Corp owner
W-2 + distribution estimates
Partnership
K-1 income estimates
Side hustle
Schedule C estimates
Deeper questions.
Why quarterly?
IRS requires quarterly payments if you'll owe $1K+ at year-end.
Due dates?
April 15, June 15, September 15, January 15.
Safe harbor?
Pay 100% of last year's tax (110% if AGI > $150K) to avoid penalty.
State estimates?
Yes — for all 41 income-tax states.
How accurate?
Based on IRS Form 1040-ES methodology.
Self-employment tax?
Included in calculation.
S-Corp distributions?
Distinguished from W-2 wages.
Year-end true-up?
Yes — final reconciliation at tax-prep time.
Start your business in the next 5 minutes.
No state-fee markup. Pay only the state fee. 60-day money-back guarantee.