If you’re a 1099 contractor (or a W-2 employee with significant non-withheld income), the IRS requires you to pay estimated taxes quarterly. Missing these payments results in penalties and interest.
Due Dates
| Quarter | Income Period | Payment Due |
|---|
| Q1 | January – March | April 15 |
| Q2 | April – May | June 15 |
| Q3 | June – August | September 15 |
| Q4 | September – December | January 15 (following year) |
Note the uneven income periods — Q2 only covers 2 months while Q3 covers 3 months. The IRS sets the dates, not a simple quarterly split.
Who Needs to Pay
You generally need to make quarterly payments if:
- You expect to owe $1,000+ in taxes after withholding and credits
- Your withholding won’t cover at least 90% of this year’s tax or 100% of last year’s tax
Most 1099 travel nurses need quarterly payments because no taxes are withheld.
W-2 employees usually have sufficient withholding, but may need quarterly payments if they have significant side income or if their withholding is too low.
Safe Harbor Rules
You can avoid underpayment penalties by meeting either of these thresholds:
- Pay 90% of your current year’s total tax liability, OR
- Pay 100% of last year’s total tax liability (110% if AGI was over $150,000)
The 100%-of-last-year rule is easier to calculate and provides certainty. TaxHomeBase shows both thresholds on the Tax Estimate page.
Calculating Your Payment
TaxHomeBase’s Tax Estimate calculates your estimated quarterly payment:
- Estimates total annual tax (federal + state + SE)
- Divides by 4 for the quarterly amount
- Compares against actual payments you’ve recorded
Underpayment Penalties
If you underpay, the IRS charges a penalty based on:
- The amount of underpayment
- The period of underpayment
- The federal short-term interest rate + 3%
The penalty is calculated per quarter, so paying late for Q1 but on time for Q2–Q4 only triggers a penalty for Q1.
How TaxHomeBase Helps
The Tax Estimate page includes a Quarterly Payments section:
- Payment cards per quarter — Status badge (Paid/Due/Overdue/Upcoming), estimated amount, due date
- Record payments — Amount, date, confirmation number, notes
- Underpayment detection — Amber flag when paid < estimated
- Summary row — Total Estimated / Total Paid / Remaining
Alerts
The notification system includes two quarterly payment alerts:
quarterly_overdue (danger) — Past the due date without paymentquarterly_due (warning) — Within 14 days of due date
