Your pay stub shows California state tax withholding, but freelance, investment, rental, or business income can leave additional tax due. If you expect that gap, decide whether to make estimated tax payments before the next installment deadline.
Here is the California-specific part: for tax year 2026, the California Franchise Tax Board (FTB) generally requires estimated tax when the expected balance is at least $500, or $250 if married or a registered domestic partner (RDP) filing separately, and withholding and credits fall below the applicable prepayment standard.
Who Must Pay Estimated Tax?
Taxpayers generally must prepay estimated tax when their expected 2026 balance meets the filing-status threshold and withholding and credits are insufficient.
The standard comparison is the smaller of 90% of the tax shown on the 2026 California return or 100% of the tax shown on the 2025 California return, including Alternative Minimum Tax.
Different rules apply to certain higher-income taxpayers, farmers and fishermen, military households, and some nonresidents or new residents. Review the 2026 Form 540-ES instructions before relying on the standard estimated tax calculation.
Takeaway: compare your expected California tax liability with withholding and credits, then check the applicable prepayment standard in the 2026 FTB Form 540-ES instructions.
The next step is calculating the estimated amount.
How Is Estimated Tax Calculated?
Estimated tax is the California state income tax you expect to owe after subtracting planned credits and expected withholding.
To calculate estimated tax payments, start with estimated adjusted gross income (AGI), determine California taxable income, calculate the applicable tax, add other required amounts, and then apply the prepayment rules in the California Estimated Tax Worksheet.
California taxable income can differ from federal taxable income because California applies its own additions, subtractions, and deduction rules.
Example: Assume a single filer calculates $8,000 of California state tax for tax year 2026, expects $5,000 of California withholding, and has no credits. Ninety percent of the current-year liability is $7,200.
If 90% is the applicable required annual amount, subtracting $5,000 of withholding leaves an estimated $2,200 to prepay. This estimated tax example is not a completed return calculation.
Estimated payment takeaway: use the 2026 FTB California Estimated Tax Worksheet because federal taxable income and California taxable income can differ.
Revisit the estimate when income changes.
When Should You Recalculate an Estimated Amount?
An estimated tax amount should be recalculated when income, deductions, credits, withholding, residency, or filing status changes materially. A new contract, stock sale, rental gain, or reduction in payroll withholding can increase the amount due.
A larger deduction or additional withholding can reduce it.
Taxpayers with uneven income can consider the annualized-income method, which aligns estimated tax payments more closely with when income was earned. The relevant underpayment calculation appears on Form 5805.
Keep the assumptions behind every estimated tax calculation so that you can explain a later change.
Estimated takeaway: update the calculation before each installment and check the annualized-income rules in the FTB instructions for Form 5805 if your income was uneven.
Once the amount is updated, select from the available payment options.
How Can You Make a Payment?
You can make estimated tax payments through FTB Web Pay, electronic funds withdrawal supported by tax software, credit card, check, or money order. Web Pay permits scheduling up to one year ahead.
Credit-card payments are processed by ACI Payments, Inc. and carry a service fee; verify the current charge on the FTB credit-card page.
Mandatory electronic-payment rules apply after an individual makes an estimated or extension payment exceeding $20,000, or files an original return showing a total tax liability over $80,000. Subsequent tax payments must generally be electronic.
Failure to follow the electronic-payment requirement can result in a penalty.
Payment takeaway: confirm the tax year and estimated tax payment type on the FTB payment screen before submitting funds.
Next, record each payment separately.
How Should You Track Payments?
Track estimated tax payments by date, amount, tax year, method, and confirmation number. The record section in Form 540-ES includes space for Web Pay or card confirmation numbers, amounts paid, prior-year overpayments applied, and totals.
Use MyFTB to check which payments the FTB has received. Keep each confirmation with your records because it can help identify a missing or misapplied credit.
If spouses or RDPs made joint tax payments but later file separately, follow the FTB allocation procedure before filing.
Payments takeaway: reconcile your records against the payment activity shown in MyFTB for the correct tax year.
Tracking also helps you manage deadlines throughout the year.
What Are the 2026 Tax-Year Due Dates?
The 2026 estimated tax installment dates are April 15, 2026; June 15, 2026; September 15, 2026; and January 15, 2027. California allocates the required annual payment as 30%, 40%, 0%, and 30%, respectively, even though the FTB lists four installment dates.
A fiscal-year filer instead uses the 15th day of the fourth, sixth, and ninth months of the fiscal year and the first month of the following year. If a deadline falls on a weekend or legal holiday, it moves to the next business day.
Confirm dates on the FTB personal due-date page.
Year takeaway: use the FTB schedule for tax year 2026 because California estimated tax installments are not four equal 25% payments.
For mailed payments, use the correct form.
When Is Form 540-ES Required?
Form 540-ES is required as the payment voucher when you pay 2026 estimated tax by mail. Use the voucher for the correct due date, enter the payment amount, and include your Social Security number (SSN) or individual taxpayer identification number (ITIN).
Make the check or money order payable to the Franchise Tax Board and mail it with the form to the Sacramento address printed in the instructions.
Do not mail the form when paying through Web Pay, electronic funds withdrawal, or credit card. Do not combine a prior-year balance with a current-year estimated tax payment.
Form 3519 serves a different purpose: paying an extension balance.
Form takeaway: match the form, tax year, payment type, and taxpayer identification details against the 2026 FTB instructions before mailing the payment.
The final check is whether your income assumptions remain accurate.
How Does Income Affect the Final Decision?
Income determines whether estimated tax is required, which prepayment standard applies, and whether annualization is useful. For tax year 2026, taxpayers whose 2025 California AGI exceeded $150,000, or $75,000 if married or an RDP filing separately, generally compare 90% of current-year tax with 110% of prior-year tax.
Taxpayers with 2026 California AGI of at least $1 million, or $500,000 when married or an RDP filing separately, must generally base estimated tax on current-year tax.
California taxable income above $1 million can also require the Behavioral Health Services Tax Worksheet. Review the official 2026 instructions for exceptions and the rules effective for tax year 2026.
Income takeaway: check your 2025 and expected 2026 California AGI against the thresholds in the 2026 FTB Form 540-ES instructions before choosing the estimated tax amount to pay.
California Taxes is an independent reference, not a government website, and this page does not provide personalized tax, legal, accounting, or investment advice.