Line 18 – California Itemized Deductions or California Standard Deduction
Decide whether to itemize your charitable contributions, medical expenses, mortgage interest paid, taxes, etc., or take the standard deduction. Your California income tax will be less if you take the larger of:
Your California itemized deductions.
Your California standard deduction.
California itemized deductions may be limited based on federal AGI. To compute limitations, use Schedule CA (540). RDPs, use your recalculated federal AGI to figure your itemized deductions.
On federal tax returns, individual taxpayers who claim the standard deduction are allowed an additional deduction for net disaster losses. For California, deductions for disaster losses are only allowed for those individual taxpayers who itemized their deductions.
If married/or an RDP and filing separate tax returns, you and your spouse/RDP must either both itemize your deductions (even if the itemized deductions of one spouse/RDP are less than the standard deduction) or both take the standard deduction.
If someone else can claim you as a dependent, you may claim the greater of the standard deduction or your itemized deductions. To figure your standard deduction, use the California Standard Deduction Worksheet for Dependents.
Itemized deductions – Figure your California itemized deductions by completing Schedule CA (540), Part II, line 1 through line 30. Enter the result on Form 540, line 18.
If you did not itemize deductions on your federal income tax return but will itemize deductions for your Form 540, first complete federal Schedule A (Form 1040), Itemized Deductions. Then check the box on Side 5, Part II of the Schedule CA (540) and complete Part II. Attach both the federal Schedule A (Form 1040) and California Schedule CA (540) to the back of your tax return.
Standard deduction – Find your standard deduction on the California Standard Deduction Chart for Most People. If you checked the box on Form 540, line 6, use the California Standard Deduction Worksheet for Dependents.