First-Time Tax Filer Guide California

Do You Need to File?

You must file a federal tax return if your gross income exceeds the filing threshold for your age and filing status. For 2025, the threshold is $14,600 for single filers under 65, $21,900 for head of household, and $29,200 for married filing jointly. You should also file even if your income is below the threshold if: you had federal income tax withheld and want a refund, you qualify for refundable credits (EITC, Child Tax Credit), or you are self-employed with net earnings of $400 or more.

For California, the filing threshold is approximately $19,310 for single filers. California residents who file a federal return generally must also file a California return.

What You Need to File

Gather these documents before starting your return: W-2s from all employers (issued by January 31), 1099s for freelance income, interest, dividends, and investment sales, Social Security number for yourself and all dependents, last year's tax return (for reference and prior-year AGI for e-filing), records of deductible expenses (if itemizing), and bank account information for direct deposit of any refund.

Federal Return Basics

Most first-time filers use Form 1040. The return calculates your taxable income (gross income minus adjustments and deductions) and your tax liability (taxable income × tax rates). You then subtract credits and withholding to determine whether you owe additional tax or are due a refund. The standard deduction ($15,000 for single filers in 2025) is the simplest approach — you only need to itemize if your deductible expenses exceed the standard deduction.

California Return Basics

California Form 540 follows a similar structure to the federal return but uses California tax rates and California-specific deductions and credits. California's standard deduction ($5,540 for single filers in 2025) is much lower than the federal standard deduction — more California taxpayers benefit from itemizing. California does not conform to all federal deductions, so your California taxable income may be different from your federal taxable income.

Common First-Timer Mistakes

The most common first-timer mistakes: (1) Forgetting to report all income — the IRS receives copies of all W-2s and 1099s and will send a CP2000 notice if your return does not match. (2) Missing the filing deadline — file on time even if you cannot pay, to avoid the failure-to-file penalty. (3) Forgetting to file a California return — the federal and California returns are separate. (4) Using the wrong filing status — head of household has different requirements than single. (5) Not claiming all available credits — the EITC, Child Tax Credit, and education credits are frequently missed.

When to Hire a Professional

Tax software handles simple returns well. Consider hiring a professional if: you are self-employed or have freelance income, you sold investments or real estate, you received an inheritance, you moved between states, you have foreign income or accounts, you received a notice from the IRS or FTB, or your situation changed significantly from last year. KDA offers a free consultation to evaluate whether professional preparation makes sense for your situation.