How to Calculate and Pay Quarterly Tax Estimates (My Exact Process)
I’ve been paying quarterly estimates for 3 years without a single penalty. The process takes me 45 minutes per quarter. Here’s the exact workflow I follow, including the Google Sheet formula I use.
The Quick Method (What Most Freelancers Should Do)
Take last year’s total tax liability. Divide by 4. Pay that amount each quarter.
This is the “safe harbor” method. If you pay 100% of last year’s tax across 4 quarterly payments, you won’t owe penalties — even if you make significantly more this year.
Example: Last year I owed $18,000 in total federal tax (income + SE). This year’s quarterly payments: $18,000 ÷ 4 = $4,500 per quarter.
If I end up owing $22,000 this year, I’ll owe $4,000 in April — but no penalties, because I hit the safe harbor.
Note: If your AGI exceeded $150,000 last year, the safe harbor is 110% of last year’s tax, not 100%.
The Precise Method (What I Actually Do)
I calculate based on actual year-to-date income for more accuracy:
My Quarterly Workflow (45 minutes)
Two weeks before the due date:
- Open FreshBooks → Reports → Profit & Loss for the quarter
- Note net income for the quarter
- Open my Google Sheet “Tax Estimates 2026”
- Enter quarter’s net income
- Sheet calculates estimated tax using this formula:
The formula:
Quarterly federal tax = (YTD net income × 0.9235 × 0.153) +
(YTD net income - (YTD SE tax ÷ 2) - standard deduction) × marginal rate
÷ number of quarters elapsedSimplified: my sheet calculates total estimated annual tax based on YTD income, then divides by how many quarters have passed.
- Compare my calculated payment to what I’ve already paid YTD
- The difference is what I owe this quarter
One week before the due date:
- Log into IRS Direct Pay (irs.gov/payments)
- Select “Estimated Tax” → “1040-ES”
- Enter payment amount and bank info
- Submit and screenshot confirmation
- Log into NC DOR for state payment
- Repeat and screenshot
- Save both screenshots in “2026 Tax Payments” Google Drive folder
Done. 45 minutes, 4 times a year = 3 hours total annual tax management.
The Payment Dates
| Quarter | Due Date | My Reminder |
|---|---|---|
| Q1 | April 15 | Calendar alert April 1 |
| Q2 | June 15 | Calendar alert June 1 |
| Q3 | September 15 | Calendar alert September 1 |
| Q4 | January 15 (next year) | Calendar alert January 1 |
Set these reminders NOW. I use Google Calendar with 2-week advance alerts. Missing a due date means automatic penalties.
State Estimated Taxes
Don’t forget state! I pay North Carolina estimated taxes through their DOR website using the same quarterly schedule. The process is similar — calculate estimated state tax liability, pay online.
If your state has income tax, you almost certainly need to make quarterly state estimates too. Check your state’s requirements.
The Bottom Line
Quarterly estimates are a 45-minute ritual four times a year. The safe harbor method (last year’s tax ÷ 4) is the simplest approach. If you want precision, calculate based on actual YTD income.
Pay on time. Screenshot confirmations. That’s the whole system.