California Bonus Tax Calculator

For a $5,000 bonus with $60,000 earned so far this year: $1,100 federal (22% flat rate), $310 Social Security, $73 Medicare, and $512 California state tax — about $1,994 total, leaving $3,006. California withholds a flat 10.2% of supplemental wages for the state, on top of the federal 22% and FICA.

It isn't, exactly: 22% is the federal flat withholding rate for supplemental wages paid separately from regular pay (37% above $1 million in a year). Your actual tax is settled on your return, where the bonus is ordinary income; if 22% over-withheld relative to your bracket, the difference comes back as refund.

Only in how withholding is calculated up front. California withholds a flat 10.2% of supplemental wages for the state, on top of the federal 22% and FICA. On your California return, a bonus is ordinary income taxed exactly like salary.

The withholding is largely fixed, but the tax isn't: putting part of the bonus into your traditional 401(k) (if your plan allows bonus deferrals) removes it from income tax entirely, and an HSA contribution does the same. Both must be arranged with payroll before the bonus is paid.