Quarterly Estimated Taxes in California: Who Owes Them, How to Calculate Them, and What Happens If You Miss a Payment
If you earn income that is not subject to automatic withholding, the IRS and the State of California expect you to pay taxes throughout the year, not just on April 15. That is the concept behind quarterly estimated tax payments, and for high earners in California, it is one of the most commonly misunderstood obligations in the tax code.
This post answers the questions I hear most often: who owes estimated taxes, how much to pay, when the payments are due, and what happens if you miss a deadline.
Who Needs to Pay Quarterly Estimated Taxes?
You generally need to make quarterly estimated tax payments if you expect to owe $1,000 or more in federal taxes after subtracting withholding and credits. California has a similar threshold: if you expect to owe more than $500 in California income tax after withholding, the state expects quarterly payments as well.
This typically applies to:
Self-employed individuals and business owners
Freelancers and independent contractors
Investors with significant dividends, capital gains, or rental income
Partners in a partnership or members of an LLC
W-2 employees with RSU vesting events, bonuses, or investment income not fully covered by payroll withholding
That last category surprises many people. You can receive a W-2 from an employer, have taxes withheld from every paycheck, and still owe estimated taxes. If your RSUs vested during the year, if you sold an appreciated investment, or if you received rental income, your withholding may fall well short of your actual liability.
This is especially common in Newport Beach and coastal Orange County, where many high earners carry concentrated equity positions, own investment real estate, and receive compensation packages with meaningful variable components. If you have ever received a large surprise tax bill in April, underpayment of quarterly estimated taxes is often part of the reason. You can read more about why this happens in Why High-Income Earners Still Owe Taxes (Even With Withholding).
When Are Estimated Tax Payments Due?
The federal estimated tax calendar has four payment periods:
Q1: April 15
Q2: June 15
Q3: September 15
Q4: January 15 of the following year
California follows a different schedule, and this difference catches a significant number of people off guard:
Q1: April 15, with 30% of estimated annual liability due
Q2: June 15, with 40% of estimated annual liability due
Q3: No payment required in California
Q4: January 15, with the remaining 30% due
California front-loads its payments. Seventy percent of your estimated annual California tax liability is due by June 15. If you are calculating your payments based on the federal schedule, you may be significantly underpaying California by mid-year.
How Much Should You Pay?
There are two methods for calculating estimated payments, each with different tradeoffs.
Safe Harbor Method 1: Pay based on last year's tax liability
At the federal level, you avoid underpayment penalties by paying at least 100% of your prior-year tax liability across the four payment periods, or 110% if your adjusted gross income exceeded $150,000 last year. California requires 100% of the prior year regardless of income level, with a different threshold applying to taxpayers with prior-year AGI above $1 million.
This is the simpler approach. You do not need to project current-year income. As long as your payments equal or exceed the prior-year threshold, the IRS will not assess a penalty, even if you end up owing more this year.
Safe Harbor Method 2: Pay 90% of your current-year liability
This method requires estimating your actual current-year income, deductions, and credits before year end. It is more accurate and requires attention throughout the year. For clients with variable income, it often produces lower payments than the prior-year method.
If your income dropped significantly from last year, the prior-year safe harbor may cause you to overpay substantially. If you had a major financial event this year, such as a business sale, large RSU vesting, or real estate transaction, estimating based on the current year is usually the better approach.
The challenge is that projecting current-year liability requires someone who can see your full financial picture. Investment gains, business income, retirement contributions, charitable strategies, and deductions all interact. This is exactly where integrated tax and financial planning pays for itself. For more on how these pieces connect, see Why Clients Need Integrated Tax and Financial Planning.
What Happens If You Miss a Payment?
Missing an estimated payment does not trigger a late-filing penalty the way missing an April 15 return does. Instead, the IRS and California each charge an underpayment penalty, calculated as interest on the amount that should have been paid from the original due date.
For 2026, the federal underpayment rate is 8% annualized. California charges 5%. The penalty is calculated per payment period, meaning missed Q1 and Q2 payments generate two separate penalty calculations, not one combined amount at year end.
The most important thing to understand: the penalty starts accruing from the original due date of the missed payment. If you missed Q1 on April 15 and are now in September, that penalty has been accruing for months. The right move is always to catch up as soon as possible and stop the penalty from growing.
What If Your Income Is Unpredictable?
Variable income creates a genuine planning challenge for estimated taxes. If you earned a large bonus in Q1 but expect a slow Q2, or if your business income fluctuates by season, paying equal one-fourth installments of your prior-year liability may result in overpaying early and underpaying later.
The IRS allows an alternative called the annualized income installment method, which lets you calculate each estimated payment based on the income you actually earned in that period, rather than an assumed equal distribution across the year. This method requires more calculation but often reduces or eliminates underpayment penalties for taxpayers whose income does not arrive evenly.
Business owners, physicians with changing compensation, real estate investors, and commission-based earners often benefit from this approach. For business owners navigating this in their first year of self-employment, How Much Should I Set Aside for Taxes as a Self-Employed Professional in California? walks through the calculation from the beginning.
A Note on High-Income Earners in California
California adds a layer of complexity for very high earners that many advisors miss. If your adjusted gross income exceeded $1 million in the prior year, California requires you to pay 90% of your current-year liability, not the standard prior-year safe harbor. The prior-year safe harbor is simply not available to you at that income level.
This means California expects you to project and pay based on what you actually earn this year, not what you paid last year. Failing to account for it is one of the most common causes of large California underpayment penalties among high earners. For context on how business income interacts with these obligations, see The Real Financial Challenges of Starting a Business After Leaving a W-2 Job.
The Bigger Picture
Estimated taxes are one of the clearest illustrations of why tax planning is not a once-a-year event. The decisions made in June and September directly affect what is owed the following April, and they interact with investment decisions, retirement contributions, charitable strategies, and business planning throughout the year.
If you are unsure whether your payments are on track, or if something changed in your financial picture this year that may have shifted your liability, that is exactly the kind of situation that benefits from a conversation with an advisor who sees the full picture. Begin the conversation.
Frequently Asked Questions
Do I owe quarterly estimated taxes if I have a W-2 job?
Possibly. If you receive income outside your W-2, such as RSU vesting proceeds, rental income, capital gains, freelance income, or investment dividends, your payroll withholding may not cover your total tax liability. If the gap is $1,000 or more at the federal level, or $500 or more in California, estimated payments may be required.
What are the quarterly estimated tax due dates in California?
California's schedule is April 15, June 15, and January 15. There is no September quarterly payment in California. California requires 30% of the estimated annual liability in April, 40% in June, and the remaining 30% in January. This front-loaded schedule differs from the federal calendar, which includes a September 15 payment.
What is the safe harbor rule for estimated taxes in California?
California's standard safe harbor requires paying 100% of the prior year's tax liability across the payment periods. However, if your prior-year adjusted gross income exceeded $1 million, California requires you to pay 90% of the current year's liability instead. The prior-year safe harbor is not available at that income level.
What happens if I miss a quarterly estimated tax payment in California?
California charges an underpayment penalty of approximately 5% annualized on the amount that was underpaid, calculated from the original due date of the missed payment. The federal rate is currently 8% annualized. Penalties are assessed per period, so catching up quickly reduces the total amount that accrues.
Can I just pay everything I owe in April instead of making quarterly payments?
No. The tax system requires that taxes be paid as income is earned throughout the year. Paying the full balance in April without having made quarterly payments will result in underpayment penalties calculated from each missed payment period.
How do I calculate my Q3 federal estimated tax payment?
Your Q3 payment, due September 15, should represent one-fourth of either your prior-year tax liability (using the 110% threshold if your prior-year AGI exceeded $150,000) or 90% of your projected current-year liability. If your income has changed significantly this year, a mid-year projection with your tax advisor is the most accurate way to determine the right amount and avoid both underpayment penalties and unnecessary overpayment.
What is the annualized income installment method?
It is an IRS-approved alternative for calculating estimated payments when income is not evenly distributed throughout the year. Instead of paying equal quarterly installments based on an annual estimate, each payment is calculated on income actually earned through the end of that period. It requires more calculation but can significantly reduce penalties for business owners, commission earners, and others with seasonal or variable income.