California’s Estimated Tax Due Dates

Here’s the California estimated tax payment schedule for individuals. Memorize it or bookmark this page, because it catches people every single year:

• April 15 — 30% of your estimated annual tax
• June 15 — 40% of your estimated annual tax
• September 15 — 0% (yes, zero — no payment due)
• January 15 — 30% of your estimated annual tax

Read that again. California skips September entirely. After your June payment, your next estimated tax isn’t due until January of the following year. This is the opposite of the federal system, where September 15 is the third quarterly payment. If you set up equal quarterly payments thinking they mirror the IRS, you’ll be short in April and June, and you’ll have made an unnecessary September payment.

For a side-by-side comparison of federal and state deadlines, see our guide on when quarterly taxes are due.

The 30/40/0/30 Split

Why does California use this odd breakdown? The FTB front-loads collections. By June 15, you’re supposed to have paid 70% of your annual estimated tax. The federal system only expects 50% by the same date. California wants more of your money sooner.

Here’s what that looks like in dollars. If your total estimated California tax for the year is $50,000:

• April 15: $15,000 (30%)
• June 15: $20,000 (40%)
• September 15: $0
• January 15: $15,000 (30%)

That September gap feels generous until you realize you already paid $35,000 by mid-June. The state got its money early. You’re the one waiting around until January to make the final payment.

Withholding from W-2s and 1099s

If you’re a W-2 employee, California income tax withholding shows up in box 17 of your W-2. That withholding counts toward your total tax payments on the 540 and reduces (or eliminates) your need for estimated payments. Most W-2 employees don’t need to make estimated payments at all — their withholding covers it.

But if you have side income, rental income, capital gains, or K-1 income on top of your W-2 wages, the withholding on your salary probably won’t cover the tax on everything. That’s when estimated payments kick in.

1099 income with California withholding (box 16 on a 1099-NEC or 1099-MISC, for example) also counts. Some payers withhold California tax for you; many don’t. Check your 1099s — don’t assume withholding happened just because it did at the federal level.

Safe Harbor: Avoiding the Penalty

California’s safe harbor rules determine whether you owe an underpayment penalty. You’re in the clear if you paid at least:

• 90% of the current year’s tax, or
• 100% of the prior year’s tax (110% if your AGI exceeded $150,000 — or $75,000 if married filing separately)

That 110% threshold is the one that bites high earners. If your 2023 California tax was $80,000, and your 2024 AGI is over $150K, you need to have paid at least $88,000 in estimated payments and withholding during 2024 to avoid the penalty — even if your actual 2024 tax turns out to be lower.

The penalty is calculated on Form 5805 (or 5805-F for farmers and fishermen). It’s not optional — the FTB will assess it automatically if your payments fell short. The interest rate fluctuates, but it’s typically been around 5-7% annually in recent years.

Common Mistakes

Number one: using federal estimated payment amounts for California. We see this constantly. Someone calculates their quarterly estimate once, divides by four, and sends the same check to both the IRS and the FTB. That works for the IRS (four equal payments of 25%). It does not work for California. You’re $5,000 short in June and $12,500 over in September.

Number two: forgetting to adjust mid-year. If you sell a stock in August for a $200,000 gain, you can’t wait until January to account for it in your California estimates. The FTB can assess a penalty on an installment-by-installment basis using the annualized income method. That said, since September has no payment due in California, the next chance to catch up is January.

Number three: not counting withholding. Your W-2 withholding is treated as paid evenly throughout the year for penalty purposes. If your employer withheld $30,000 in California tax across the year, that counts as $7,500 per quarter — even if most of the withholding happened in December due to a bonus. This can actually help you avoid an underpayment penalty in the early quarters.

Where This Shows Up on the 540

Estimated payments and withholding appear in the payments section of your Form 540, after all credits (like the PTE credit, Other State Tax Credit, and renter’s credit) have been applied. The total of your withholding plus estimated payments is compared against your total tax after credits. If your payments exceed the tax, you get a refund. If they fall short, you owe the balance — plus potentially a penalty if you didn’t hit the safe harbor.