About Deductions

This estimate includes standard federal withholding, FICA taxes (7.65%), and state income tax rates applicable in CALIFORNIA. Local county taxes are factored in where applicable.

Understanding Your Paycheck in CALIFORNIA

When you receive a paycheck in San Mateo County, the amount you see on the face of the stub is the result of several mandatory and optional deductions. Three core withholdings are required by law:

• Federal Income Tax: Collected by the Internal Revenue Service (IRS) based on the information you provide on your Form W‑4.
• State Income Tax: Collected by the California Franchise Tax Board (FTB) and calculated using California’s own tax brackets.
• FICA (Social Security and Medicare): A combined 7.65 % of gross wages (6.2 % for Social Security up to the annual wage base and 1.45 % for Medicare; an extra 0.9 % Medicare surcharge applies to wages above $200,000 for single filers).

In addition to these, California employers must also contribute to state unemployment insurance (SUI) and, for many employees, to State Disability Insurance (SDI). While SUI is an employer‑only cost, the SDI withholding (currently 1.1 % up to a quarterly wage limit) appears on your pay stub and reduces your take‑home pay.

Federal Tax Withholding

The amount withheld for federal income tax hinges on the filing status, number of dependents, and any additional amount you request on your Form W‑4. The IRS uses a progressive tax schedule for 2024, ranging from 10 % on the first $11,000 (single) to 37 % on income over $539,900. Your employer applies the W‑4 information to the IRS’s wage‑bracket tables to estimate the correct withholding for each pay period.

• Step 1 – Filing Status: Single, Married filing jointly, Married filing separately, or Head of Household.
• Step 2 – Multiple Jobs or Spouse Works: Indicates whether you have more than one job, which can increase your effective withholding.
• Step 3 – Dependents: Credits for qualifying children and other dependents lower your taxable wage amount.
• Step 4 – Other Adjustments: Allows you to include other income, deductions, or an extra flat amount you want taken out each paycheck.

Because the tax code is progressive, each additional dollar you earn is taxed at the marginal rate for your income tier, not at a flat rate. Adjusting your W‑4 to reflect accurate life‑stage changes can prevent large refunds or unexpected tax bills.

State & Local Taxes

California’s state income tax is also progressive, with nine brackets for 2024 ranging from 1 % on the first $10,099 (single) to 12.3 % on income above $625,369. An additional 1 % Mental Health Services Tax applies to taxable income over $1 million. The state uses the same filing status categories as the federal system, but the brackets and rates differ, so both calculations appear separately on your stub.

San Mateo County does not impose a separate county income tax. However, the county does levy a payroll expense tax on certain employers (generally businesses with payrolls exceeding $1 million). This tax is an employer cost and does not affect employee take‑home pay directly, but it can influence overall compensation packages offered by local businesses.

Maximising Your Take-Home Pay

While you cannot eliminate mandatory withholdings, you can strategically reduce taxable income and increase net pay:

• Adjust Your W‑4: If you consistently receive large refunds, consider claiming fewer dependents or decreasing the extra withholding amount.
• Contribute to a 401(k) or 403(b): Pre‑tax contributions lower both federal and state taxable wages. In 2024, you may defer up to $23,000 ($30,500 if age 50+).
• Health Savings Account (HSA): If you have a high‑deductible health plan, HSA contributions are pre‑tax and can be deducted from wages before federal and state taxes.
• Flexible Spending Accounts (FSAs): Employer‑offered FSAs for medical or dependent care reduce taxable earnings.
• Consider Roth Options: While Roth contributions are post‑tax, they allow tax‑free growth and withdrawals, potentially reducing taxable income in future years.
• Review Benefits Elections Annually: Changes in health insurance premiums, commuter benefits, or voluntary life insurance can affect taxable wages.

Using the San Mateo County take‑home pay calculator with accurate W‑4, benefit, and retirement inputs will give you a clear picture of how each decision impacts your net earnings, empowering you to make informed financial choices.