The California safe harbor rule for estimated tax payments lets you avoid a Franchise Tax Board underpayment penalty by prepaying, across the year, the lower of 90% of your current-year tax or 100% of last year’s tax (110% if your prior-year California AGI was above $150,000). Hit that total on California’s uneven 30/40/0/30 installment schedule and you’re protected, even if your final bill ends up much higher.
Who Has to Make Estimated Payments at All
You only need to worry about estimated payments if you expect to owe at least $500 in California tax after withholding and credits. The threshold drops to $250 if you’re married or in a registered domestic partnership and filing separately.1Franchise Tax Board. Estimated Tax Payments If withholding already covers your liability, nothing else is required of you regardless of income.
Even above that minimum, you’re off the hook if your withholding and credits already cover the smaller of 90% of your current-year tax or 100% of your prior-year tax (including any alternative minimum tax).2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
The Two Safe Harbor Numbers
If your prior-year AGI was $150,000 or less ($75,000 or less if married filing separately), you pick whichever of these produces a smaller required payment:
- 90% of your current-year California tax. Accurate if your income is predictable; risky if it isn’t.
- 100% of your prior-year California tax. The number is already fixed on last year’s Form 540, so there’s no guessing.
The prior-year method is the one most people lean on because it removes the forecasting problem. If last year’s tax was $12,000, prepaying $12,000 across the year protects you fully, even if your actual liability turns out to be $18,000.1Franchise Tax Board. Estimated Tax Payments
If you applied last year’s refund to this year’s estimated tax, that credit counts toward your first installment. Reduce the April payment accordingly so you don’t pay twice.2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
Higher Earners Pay 110% of Prior-Year Tax
If your prior-year California AGI exceeded $150,000 ($75,000 for married filing separately), the prior-year safe harbor rises from 100% to 110% of last year’s tax.1Franchise Tax Board. Estimated Tax Payments You can still choose 90% of current-year tax if that produces a smaller number.
The $1 Million AGI Rule Removes the Prior-Year Option
Once your current-year California AGI reaches $1,000,000 or more ($500,000 if married filing separately), the prior-year safe harbor disappears. You have to pay at least 90% of your actual current-year tax, with no fallback to what you paid before.2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
For high earners with volatile income, this is the rule to watch. A $400,000 year followed by a $1,200,000 year means last year’s tax is no safety net. You need a current-year estimate that lands within 10% of your actual liability, or you’ll owe a penalty on the shortfall.
California’s Uneven Installment Schedule
This is the piece that catches people most often. The IRS splits estimates into four equal 25% installments. California does not. The FTB uses:1Franchise Tax Board. Estimated Tax Payments
- April 15 — 30% of your required annual payment
- June 15 — 40%
- September 15 — 0% (no payment due)
- January 15 of the following year — 30%
June is the biggest installment, and September has no payment at all. If you set up four equal quarterly transfers out of habit, you’ll underpay in June and can trigger a penalty on that installment even when your yearly total is right.
If a due date lands on a weekend or legal holiday, it moves to the next business day.3Franchise Tax Board. Due Dates Businesses You can also skip the January installment if you file your return and pay the full balance by January 31.2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
When Your Income Is Uneven: The Annualized Method
If your income arrives in bursts, like a Q4 bonus, seasonal business revenue, or a one-time capital gain, the standard schedule can penalize you for not paying tax on money you hadn’t earned yet. The annualized income installment method bases each installment on what you actually earned through the end of that period. Early payments shrink, later ones grow, and the total still has to cover the required percentage of tax on the annualized income through each date. Use Part III of FTB Form 5805 and attach it to your return.4Franchise Tax Board. 2024 Instructions for Form FTB 5805 Underpayment of Estimated Tax by Individuals and Fiduciaries
Farmers, Fishermen, and New Residents
If at least two-thirds of your gross income comes from farming or fishing, the safe harbor eases to 66⅔% of current-year tax, and the whole year’s payment is due on a single January 15 deadline. File and pay the full balance by March 1 (or the next business day) and no estimated payment is required.2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
New residents and nonresidents who had no California tax liability in the prior year are exempt from estimated payments. With no prior-year California return, the prior-year safe harbor has nothing to measure against, and the FTB doesn’t penalize the gap.2Franchise Tax Board. 2025 Instructions for Form 540-ES Estimated Tax for Individuals
What Happens If You Miss
Missing the safe harbor isn’t a flat fine. The penalty works like interest on the amount you should have paid, running from each installment due date until the shortfall is covered. The FTB calculates it separately for each installment, so an April shortage doesn’t automatically poison a June payment that was on time.
The FTB resets the estimate penalty rate every six months. For July 1, 2025 through June 30, 2026, the rate is 4%, compounded daily.5Franchise Tax Board. Interest and Estimate Penalty Rates Because the clock runs on each installment independently, catching up early matters: a shortfall left outstanding until you file in October costs far more than one you cover within weeks.
Mandatory Electronic Payment Above $20,000
If any single estimated or extension payment exceeds $20,000, or if your total tax liability on an original return exceeds $80,000, California requires you to pay electronically.6Franchise Tax Board. Mandatory e-Pay for Individuals Paying by paper check above those thresholds costs a separate 1% penalty on the amount paid incorrectly.7Franchise Tax Board. Common Penalties and Fees On a $25,000 payment, that’s $250 for using the wrong method. The FTB accepts Web Pay, electronic funds transfer, and card payments (cards carry a processing fee of roughly 2.3%).
Form 5805 and Waivers
Form 5805 is where you either show you met a safe harbor or calculate what you owe if you didn’t. Attach it to your Form 540 or 540NR.8Franchise Tax Board. 2024 Form 5805 Underpayment of Estimated Tax by Individuals and Fiduciaries The FTB will usually figure the penalty for you, so filing the form yourself is optional in most cases. You do need to file it if you used the annualized income method, are requesting a waiver, or want to check the FTB’s math.
Waivers are limited. The two grounds the FTB recognizes are a casualty, disaster, or unusual circumstance where the shortfall came from reasonable cause rather than neglect, and retirement after age 62 or disability occurring during the tax year or the one before it, again where reasonable cause applies.9Franchise Tax Board. Instructions for Form FTB 5805 Underpayment of Estimated Tax by Individuals and Fiduciaries To request one, check “Yes” on Part I, Question 1 of Form 5805, add a short explanation, calculate the penalty as if no waiver existed, then write the amount you want waived on the dotted line next to the penalty total.4Franchise Tax Board. 2024 Instructions for Form FTB 5805 Underpayment of Estimated Tax by Individuals and Fiduciaries If the FTB has already assessed the penalty, send the form separately with a written explanation to ask for abatement.