Do I Need to Pay Estimated Taxes on RSU Income?

If you work in tech and receive RSUs as part of your compensation, there's a good chance your employer isn't withholding enough tax when those shares vest. The flat 22% federal supplemental withholding rate rarely matches your actual marginal rate — and the IRS expects you to make up the difference throughout the year, not just at tax time.

This guide explains when estimated tax payments are required, how to calculate them, and the strategies that prevent underpayment penalties.

When Estimated Tax Payments Are Required

The IRS requires estimated tax payments when you expect to owe $1,000 or more in federal tax at filing that isn't covered by withholding (IRC Section 6654). For most tech employees with significant RSU income, this threshold is easily crossed.

Here's the test: if your total tax liability minus your total withholding (from salary plus RSUs) will leave you owing $1,000+, you either need to:

1. Make quarterly estimated payments using IRS Form 1040-ES, or
2. Increase your W-4 withholding so additional tax is taken from your paycheck

If you fail to do either, the IRS charges an underpayment penalty — essentially interest on the tax you should have paid throughout the year.

The Safe Harbor Rules

The IRS provides two "safe harbor" methods that protect you from underpayment penalties, even if you end up owing at tax time:

1. 90% of current year tax — Your withholding plus estimated payments cover at least 90% of your actual 2026 tax liability.
2. 110% of prior year tax — Your withholding plus estimated payments cover at least 110% of your 2025 tax liability (100% if AGI was under $150,000).

Most people with variable RSU income use the prior-year safe harbor (option 2) because it's predictable. You know your 2025 tax liability from your filed return, so you can calculate exactly how much to withhold or pay in estimates.

Worked example of the 110% safe harbor:

As long as your total withholding + estimated payments reach $88,000, you won't owe penalties — even if your actual 2026 tax turns out to be $100,000+. You'll still owe the difference at filing, but without the penalty.

Why 22% Withholding Creates a Shortfall

RSU vesting income is classified as "supplemental wages" under IRS rules. Employers are required to withhold federal tax at a flat 22% rate on supplemental wages up to $1 million (and 37% on amounts above $1 million). This rate has nothing to do with your actual tax bracket.

For a tech employee earning $200,000 in salary with $150,000 in RSU vesting, the math works like this:

The withholding gap:

And that's just federal. Add California state tax at 9.3% marginal (with only 10.23% supplemental withholding, which roughly covers it) or New York at 8.82% marginal (with 11.70% supplemental withholding, which over-covers it), and the total picture varies by state.

For a California resident in this scenario, the combined federal + state shortfall is typically $12,000 to $18,000 — well above the $1,000 threshold that triggers estimated payment requirements.

Example 1: $150K RSU Vest, $200K Salary, California Resident

Let's walk through the full calculation for this common scenario:

Annual numbers:

• Salary: $200,000
• RSU vesting: $150,000 (spread across 4 quarterly vests of $37,500 each)
• Filing status: Single
• State: California

Federal tax calculation:

• Total W-2: $350,000
• Taxable income: $335,000 (after $15,000 standard deduction)
• Total federal tax: ~$77,000
• Federal withholding from salary: ~$38,000
• Federal withholding from RSUs (22%): $33,000
• Total federal withheld: ~$71,000
• Federal shortfall: ~$6,000

California state tax:

• CA taxable income: ~$344,300 (after $5,706 CA standard deduction)
• CA tax liability: ~$25,500
• CA withholding from RSUs (10.23%): ~$15,345
• CA withholding from salary: ~$9,500
• CA shortfall: ~$650

Total combined shortfall: ~$6,650

Since this exceeds $1,000, quarterly estimated payments are required unless you increase your W-4 withholding.

Example 2: Same Income, Washington/Texas (No State Tax)

Same scenario — $200K salary, $150K RSU — but in a no-income-tax state:

Wait — the shortfall is higher in a no-tax state? Yes. In California, the state supplemental withholding (10.23% = $15,345) exceeds the actual state tax owed (~$14,700), creating a ~$650 surplus that partially offsets the federal gap. In Washington or Texas, there's no state withholding offset — the entire federal shortfall hits you at tax time.

The lesson: no-income-tax states simplify your taxes but don't eliminate estimated payment requirements.

How to Pay Estimated Taxes

The IRS and states each have their own payment systems:

IRS Form 1040-ES Due Dates for 2026

Estimated tax payments are due quarterly on these dates:

Note the uneven periods — Q2 only covers two months. If a large RSU vest happens in Q1, you may owe a larger estimated payment for that quarter.

How to Calculate Your Estimated Payments

Step 1: Estimate your total 2026 tax liability. Include all income sources: salary, RSUs, bonuses, investment income.

Step 2: Subtract your expected withholding. Your salary withholding is on your pay stubs. RSU withholding is 22% federal + your state supplemental rate.

Step 3: If the gap exceeds $1,000, divide by the number of remaining quarters and make payments via IRS Direct Pay or EFTPS.

Or use the prior-year safe harbor: Take your 2025 total tax, multiply by 110%, subtract expected 2026 withholding, and divide the gap by 4 (or remaining quarters).

Alternative: Increase Your W-4 Withholding

Many employees prefer adjusting their W-4 over making quarterly estimated payments. You can request additional federal withholding on Line 4(c) of your W-4 form.

Advantages of W-4 adjustment:

• Automatic — no quarterly deadlines to remember
• Withholding from paychecks is treated as paid evenly throughout the year (even if you increase mid-year)
• No need to file Form 1040-ES

Specific Line 4(c) example:

• Your estimated annual shortfall: $14,400
• Remaining semi-monthly pay periods: 24
• W-4 Line 4(c) amount: $600
• Result: $600 extra withheld × 24 = $14,400 additional withholding

Submit the updated W-4 to your employer's HR/payroll system. The increase takes effect on the next payroll cycle.

This approach works especially well if your RSU vesting is predictable. If your vesting schedule is front-loaded or back-loaded, estimated payments might give you more control over cash flow timing.

The Underpayment Penalty

If you don't meet either safe harbor, the IRS charges a penalty under IRC Section 6654, calculated as interest on the underpaid amount for each quarter. The penalty rate is the federal short-term rate plus 3 percentage points, adjusted quarterly.

Current penalty rate: approximately 7-8% annualized (varies by quarter).

Worked penalty calculation: Suppose you owe $14,400 for the year, paid nothing in estimates, and don't meet either safe harbor. Penalty for each quarter:

The penalty is calculated per quarter, so even if you catch up in Q4, you'll owe penalties for earlier quarters where you were underpaid. This is why proactive planning at the beginning of the year is so important.

When You Can Skip Estimated Payments

You may not need to make estimated payments if:

• Your withholding already covers 110% of your prior-year tax (common if your salary withholding is high and RSU income is modest relative to salary)
• You had no tax liability in the prior year
• Your RSUs vest late in Q4 (you may be able to increase W-4 withholding in the final pay periods to cover the gap)

Next Steps

1. Calculate your exact shortfall using our RSU Calculator — it factors in your salary, RSU income, state, and filing status to show the precise withholding gap.
2. Review the brackets that apply to your income in our 2026 Federal Tax Brackets reference.
3. Understand your overall RSU tax burden in our guides on how RSUs are taxed and RSU tax withholding.
4. If you also hold ISOs, see our guide on estimated taxes after ISO exercise — AMT creates a separate estimated payment requirement.
5. For a comprehensive overview, read our quarterly estimated tax guide for equity compensation.
6. Check your state-specific withholding rules — California under-withholds at high incomes while New York often over-withholds. See our California income tax guide and New York income tax guide for state-level details.

Frequently Asked Questions

Are estimated tax payments deductible? No. Estimated tax payments are prepayments of your tax liability — not a deduction. They reduce what you owe at filing, but they don't reduce your taxable income. Think of them like regular withholding from your paycheck: it's tax you're paying, not an expense you're writing off.

What if I overpay estimated taxes? You'll get the excess back as a refund when you file your return, or you can apply the overpayment to next year's estimated taxes. There's no penalty for overpaying — only for underpaying.

Can my employer withhold more on RSUs instead of me making estimated payments? Not directly on the RSU withholding itself (that's fixed at the supplemental rate). However, you can increase your W-4 withholding on your regular salary paychecks via Line 4(c), which achieves the same result. Some brokers also allow you to set a higher sell-to-cover percentage — see our RSU withholding guide for details.

Do I need state estimated payments too? Yes, if your state has income tax and your state withholding doesn't cover your state tax liability. California, New York, and most other income-tax states have their own estimated payment requirements with their own forms and deadlines. California's required payment schedule (30/40/0/30) differs from the federal equal-quarter approach.

What is the annualized income installment method? If your income is heavily concentrated in one quarter (e.g., a large Q1 RSU vest with no vesting the rest of the year), you can use the annualized income installment method (IRS Form 2210, Schedule AI) to reduce penalties. This method calculates your required payment based on the income actually received in each quarter, rather than assuming equal quarterly income. It's complex but can save significant penalty amounts for lumpy income patterns.