> ## Documentation Index
> Fetch the complete documentation index at: https://docs.taxhomebase.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Quarterly Estimated Payments

> Due dates, safe harbor rules, and how to avoid underpayment penalties.

<Snippet file="tax-disclaimer.mdx" />

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) |

<Warning>
  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.
</Warning>

## 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:

1. **Pay 90%** of your current year's total tax liability, OR
2. **Pay 100%** of last year's total tax liability (110% if AGI was over \$150,000)

<Tip>
  The 100%-of-last-year rule is easier to calculate and provides certainty. TaxHomeBase shows both thresholds on the Tax Estimate page.
</Tip>

## Calculating Your Payment

TaxHomeBase's [Tax Estimate](/guides/tax-estimate) calculates your estimated quarterly payment:

1. Estimates total annual tax (federal + state + SE)
2. Divides by 4 for the quarterly amount
3. 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](/guides/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 payment
* `quarterly_due` (warning) — Within 14 days of due date