This tool is intended to help you determine how much California income tax you would owe given the data you provide. The California income tax is based on the federal adjusted gross income (AGI), and then, additions and subtractions are made to account for differences in the federal and state tax laws. This means you need to provide and accurate estimate of the federal AGI and some of the values that were used to calculate it.
The blue fields are computed from the information you provide. The green fields are where you enter information. The first column shows where the information can be found in the tax return. Click this link for more help with this tool.
Taxpayer's Name
Version
Filing Status
Today's Date
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Taxpayer's Birthday
Taxpayer's Age
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Spouse's Birthday
Spouse's Age
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The tax formula below describes, at a high level, how the tax is calculated. The value of each item in the tax formula is shown in the Estimated Tax Calculation. You can see a brief description of any of the items by moving the mouse over the calculated value in the Estimated Tax Calculation.
540, line 17, State AGI
= Federal AGI - Subtractions + Additions
540, line 19, Taxable Income
= State AGI - Deductions
540, line 31, Income Tax
= Tax on Taxable Income
540, line 35, Total Tax
= Income Tax - Exemptions - Non-refundable Credits + Other Taxes
540, line 111, Refund / Amount Due
= Payments + Refundable Credits - Total Tax
540, line 11
Exemptions
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540, line 14
Subtractions
0
540, line 16
Additions
0
540, line 18
Deductions
0
540, line 48
Non-refundable Credits
0
540, line 74-77
Refundable Credits
0
540, line 64
Other Taxes
0
540, line 78
Payments
0
540, line 17
State AGI
0
540, line 19
Taxable Income
0
540, line 31
Income Tax
0
540, line 35
Total Tax
0
540, line 111-115
Refund (+) / Amount Due (-)
0
540-ES
Estimated Payment April (30%)
0
540-ES
Estimated Payment June (40%)
0
540-ES
Estimated Payment September (0%)
0
540-ES
Estimated Payment January (30%)
0
540, line 13
Federal AGI
540, line 10
Number of Dependents
CA 540, part IA, line 2
Interest on U. S. Treasury Obligations
CA 540, part IA, line 5
Military Retirement Income
CA 540, part IA, line 6b
Taxable Social Security
CA 540, part IB, line 1
State Tax Refund
CA 540, part IB, line 7
Unemployment Income
CA 540, part IB, line 8b
California Lottery Winnings
CA 540, part IB, line 8f
Non-qualified HSA Distributions
CA 540, part IC, line 19
Alimony Paid
CA 540, part IC, line 24
Other Subtractions
CA 540, part IA, line 1h
HSA Employer Contributions
CA 540, part IB, line 2
Alimony Received
CA 540, part IB, line 8c
Home Loan Debt Cancellation
CA 540, part IB, line 8c
Employer Paid Student Loan Payments
CA 540, part IC, line 11
Educator Expenses
CA 540, part IC, line 13
HSA Contributions
CA 540, part IC, line 20
IRA Contributions
CA 540, part IC, line 24
Other Additions
CA 540, part II, line 17
Federal Itemized Deductions
CA 540, part II, line 5a
State Income Tax or Sales Tax
CA 540, part II, line 4
Qualified HSA Distributions
CA 540, part II, line 5e
SALT Limit Excess
CA 540, part II, line 8a
Home Mortgage Interest Limit
CA 540, part II, line 20
Tax Preparation Fee
CA 540, part II, line 21
Safe Deposit Box
CA 540, part II, line 21
Investment Fee
CA 540, part II, line 16
Other Deductions
540, line 92
Shared Responsibility Penalty
540, line 112
Interest and Penalties
540, line 113
Underpayment of Estimated Tax
540, line 91
Use Tax
540, line 63
Other Taxes
540, line 40
Child and Dependent Care Credit
540, line 46
Renter's Credit
540, line 45
Other Non-refundable Credits
540, line 75
Earned Income Tax Credit (EITC)
540, line 76
Young Child Tax Credit
540, line 77
Foster Youth Tax Credit
540, line 78
Other Refundable Credits
540, line 71
Withholding
540, line 72
Estimated Payments
540, line 78
Other Payments
540, line 110
Contributions
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Selecting a year from this drop-down list will change the estimated tax calculator to use the tax tables for that year. It will continue to use the data that has already been entered.
Pressing the "Save" button will save the data in the estimated tax calculator to a text file named "EstimatedTax_CA.txt" in your Downloads folder. This data can be reloaded by pressing the "Restore" button.
Pressing the "Restore" button will reload the estimated tax calculator with information that was previously saved.
This is a button that causes additional internal (debugging) data values to be displayed. When the information is displayed, it is located at the bottom of the page. The symbol on the button is a ladybug. When the ladybug is black and white, the debugging information is hidden; when the ladybug is red, the debugging information is displayed.
This is the name of the taxpayer. It is only used to identify the taxpayer that the information belongs to. This may be useful if the information is saved or printed.
Select a value from the drop-down list. The filing status is used to determine a few things in the tax calculation, such as the standard deduction, the tax bracket, and certain tax benefits.
This is used to determine if the taxpayer will be 65 or older at the end of the tax year.
This is used to determine if the spouse will be 65 or older at the end of the tax year.
This is the current version of the tax tools. The version number is actually a link that you can click on to see the version history log.
This is only used to help identify the information if it is saved or printed.
This is the age the taxpayer will be at the end of the tax year. It is used to determine the number of exemptions the taxpayer will receive.
This is the age the spouse will be at the end of the tax year. It is used to determine the number of exemptions the taxpayer will receive.
Exemptions are the personal exemption for the taxpayer and spouse and the dependent exemption for each dependent. The taxpayer and spouse also get an additional exemptions if they are 65 or older and if they are blind. The number of exemptions is multiplied by the amount of the corresponding personal exemption and dependent exemption to arrive at the total amount of the exemptions.
The way the "subtractions" are calculated on the Calitornia tax return may not be intuitive. First, it adds together the items that are taxed on the federal tax return but not the California tax return (form CA 540, sections 1A and 1B). These will be subtracted from the federal AGI, as you would expect. Then, it adds together the federal adjustments (above the line deductions, form CA 540, section 1C) that are not allowed by California. These are then subtracted from the subtractions (rather than adding them as additions).
The way the "additions" are calculated on the Calitornia tax return is the opposite of the subtractions. The items that are not taxed on the federal tax return but are taxed on the California tax return are added together (form CA 540, sections 1A and 1B). These will be added to the federal AGI. Then, the federal adjustments (above the line deductions, form CA 540, section 1C) that are allowed by California are added together. These are then subtracted from the additions (rather than subtracting them as subtractions).
This is an amount that can be subtracted from the state AGI before the tax is computed. It is either the standard deduction or the sum of your itemized deductions, whichever is larger. State itemized deductions are derived from the federal itemized deductions with adjustments to account for the differences between the federal and state tax laws.
Credits are amounts that are subtracted from your tax (as compared to deductions, which are subtracted from your taxable income). At most, non-refundable credits can reduce your tax to $0.
While non-refundable credits can reduce your tax to $0, refundable credits can reduce your tax below $0, which results in you receiving money back.
These are other uncommon taxes, such as the Alternative Minimum Tax (AMT) or the Behavior Health Services Tax.
This is the amount of tax you already paid during the tax year; for example, withholding or estimated payments.
The federal AGI is used as the starting point for the state AGI, but first, the federal AGI must be adjusted to account for the differences between the federal and state tax laws.
Taxable income is the state SGI minus deductions. The state allows you to use either the standard deduction or itemized deduction regardless of which was used on the federal tax return. Since the state standard deduction is much lower than the federal standard deduction, it may be beneficial to itemize deductions for the state even if the standard deduction is more beneficial on the federal tax return.
This is the amount of tax due from the taxable income.
This is the tax on your taxable income plus any other taxes and with the non-refundable credits subtracted.
This is the amount of tax that is owed. If it is positive, it is the tax due. If it is negative, it is the amount overpaid (refund).
The estimated payments are calculated as the amount you owe plus the amount of estimated taxes you paid. If the amount is less than $500, estimated payments are not required; otherwise, they need to be paid in four unequal quarterly payments. The first and fourth payments should be 30% of the total, the second payment should be 40% of the total, and the third payment is not needed.
This is the number of dependents that you are claiming (the taxpayer and spouse are not dependents).
This is the amount of the Adjusted Gross Income (AGI) from the federal tax return. This is used at the basis for the state income tax calculation with adjustments (additions and subtractions) to this amount to account for the differences between the federal and state tax laws.
This is the amount of the itemized deductions from the federal tax return.
Enter the amount of interest from U. S. Treasury obligations. U. S. Treasury obligations, including treasury bills, notes, and bonds, are taxable on the federal tax return, but not taxable on the California tax return.
Enter the amount of military retirement income from the Defense Finance Accounting Service (DFAS) up to $20,000. For tax years 2025 to 2029, up to $20,000 of military retirement income from the DFAS (EIN 34-0727612) is not taxed on the California tax return. The taxpayer or spouse (or surviving spouse or either) must have been uniformed military, not civilian, receiving a pension from the DFAS.
Enter the amount of Social Security benefits that are taxed on the federal tax return. Social Security benefits are partially taxed on the federal return but are not taxed at all by California.
If a refund was receeived from last year's California tax return, enter the amount that is taxable on the federal tax return. A state tax refund may be taxable on the federal tax return if the state income tax used as a deduction on the previous year's federal tax return. The state tax refund is not taxable on the California tax return.
Enter the amount of unemployment income you received. This is taxable on the federal tax return, but is not on the California tax return.
Enter the amount of winnings from the California Lottery. Gambling winnings are taxed on both the federal and California tax returns; however, California does not tax winnings from the California Lottery. Since you can deduct gambling losses up to the amount of gambling winnings, you may need to adjust the amount deducted as well.
Enter the amount of distributions from an HSA that were not spent on qualified medecial expenses. These distributions are taxable on the federal tax return, but California does not exempt contributions to an HSA from taxes, so it does not tax the distributions.
Enter the amount of alimony you paid this year if you were divorced after 2018. If you were divorced after 2018 and paid alimony, the alimony is not deductible on the federal tax return, but it is deductible on the California tax return. For a divorce that was settled in 2018 or earlier, alimony paid can be deducted on both the federal and California tax returns, so no adjustment is needed.
This is a catch all field for other items that need to be subtracted from the federal AGI and are not covered in one of the other fields.
Enter the amount your employer contributed to your HSA. Employer contributions to your HSA are shown on your W-2 form, box 12, code W. This income not taxed on the federal tax return, but California does not exempt contributions to an HSA from taxes, so it is taxable income on the California tax return.
Enter the amount of alimony you received this year if you were divorced after 2018. If you were divorced after 2018 and received alimony, the alimony is not taxable on the federal tax return, but it is taxable on the California tax return. For a divorce that was settled in 2018 or earlier, alimony received can be taxed on both the federal and California tax returns, so no adjustment is needed.
If you had a home loan canceled, enter the amount of the loan. California law does not conform to federal law regarding the exclusion of income from the cancellation of a loan on your principle residence occurring after 2017.
Enter the amount of student loan payments made by your employer. California does not conform to the CARES Act regarding the exclusion of student loan payments made on behalf of an employee by an employer.
Enter the amount of educator expenses excluded from income on the federal tax return. On the federal return, educators can deduct up to $300 each for the taxpayer and spouse for unreimbursed classroom expenses. The state does not allow this federal adjustment.
Enter the amount of HSA contributions you made. Federal law allows a deduction for contributions to an HSA, but the state does not allow this deduction.
The age limit for making a tax deferred contribution to an IRA was removed from the federal tax return, but the age limit is still 70 1/2 for the state. If you made a tax deferred contribution to your IRA and you are over 70 1/2, that contribution is taxable on the California tax return.
This is a catch all field for other items that need to be added to the federal AGI and are not covered in one of the other fields.
The state income tax or sales tax is not deductible on the California tax return.
Since contributions to an HSA are not tax deferred on the California tax return, qualified distributions from an HSA are qualified medical deductions on the California tax return if they exceed 7.5% of the federal AGI.
The deduction for state and local taxes (SALT) is limited on the federal tax return but not the California tax return. If your state and local tax deduction minus the state income tax exceeds this limit, enter the excess amount here.
Federal law limits the deduction for home mortgage interest to a $750,000 loan. The state limit is 1,000,000. If your home loan is over $750,000, enter the additional interest deduction here.
Enter tax perperation fees. This is one of several miscellaneous deduction that are deductible if they exceed 2% of federal AGI. The miscellaneous deduction are suspended on the federal tax return, but not the California tax return.
Enter the cost of a safe deposit box here. This is one of several miscellaneous deduction that are deductible if they exceed 2% of federal AGI. The miscellaneous deduction are suspended on the federal tax return, but not the California tax return.
Enter investment and financial advisor fees here. This is one of several miscellaneous deduction that re deductible if they exceed 2% of federal AGI. The miscellaneous deduction are suspended on the federal tax return, but not the California tax return.
This is a catch all field for other deductions that need to be deducted from the state AGI and are not covered in one of the other fields.
Interest and penalties may be charged, for example, for late filing or late payment.
There may be a penalty for underpayment of taxes if, for example, payments are less than 90% of your current tax liability.
Use tax is a tax imposed on goods and services that were purchased without paying sales tax.
This is a catch all field for other taxes that need to be added to the state AGI and are not covered in one of the other fields.
You may be able for this credit if you paid someone to care for your dependent that is under age 13 or a dependent who is incapable of caring for themself. To qualify for this credit, your federal AGI must be less than $100,000.
You may qualify for this credit if you paid rent for at least six months during the year on your principal residence located in California.
This is a catch all field for non-refundable credits not covered in one of the other fields.
Working families making up to $32,900 may qualify for the earned income tax credit (EITC).
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A taxpayer who qualifies for the Earned Income Tax Credit or would been, but has no earned income, and has a qualifying child under six years old, may qualify for this credit. The maximum credit is $1,189 and your AGI must be less than $32,901.
This is a catch all field for refundable credits not covered in one of the other fields.
This is the amount of California tax that was withheld, for example, from your paycheck (see W-2 form) during the year.
This is the amount of estimated taxes that you paid quarterly during the year.
This is a catch all field for other payments not covered in one of the other fields.
Contributions are voluntary contributions to various causes that can be made through the California tax return.