California (CA) Home Office Deduction Calculator
Tax year: 2026 · Figures for Tax Year 2026 · Source: IRS
Built and audited by the CalcSumly Engineering Team using official IRS and State Department of Revenue data.
Your Schedule C net profit before the home office deduction.
Square footage of your dedicated, exclusively-business workspace.
Total square footage of your home.
Rent or mortgage interest, utilities, insurance, and repairs.
Simplified method
$750
$5/sqft × 150 sqft · 2026
Actual method
Recommended$1,800
10.0% of home × expenses · 2026
How the California (CA) home office deduction calculator works
This calculator estimates your total tax savings from the home office deduction in California for 2026. It computes tax at your current net profit, then again at net profit minus the deduction, and reports the difference across three tax layers:
- SE tax savings. The deduction reduces Schedule C net profit before SE tax is calculated. SE tax is 15.3% on 92.35% of net profit (Social Security 12.4% capped at $184,500, plus Medicare 2.9% uncapped). A $1,500 deduction saves roughly $212 in SE tax regardless of state.
- Federal income tax savings. Lower net profit reduces both the deductible half of SE tax and federal AGI, which cascades into lower federal taxable income. At the 22% bracket, a $1,500 deduction saves roughly $307 in federal income tax.
- California state income tax savings. California taxes federal AGI minus the state standard deduction, so both the simplified and actual home office methods reduce CA taxable income automatically.
Two IRS methods compared
- Simplified method (Rev. Proc. 2013-13). $5 per square foot of dedicated office space, up to 300 sqft, maximum $1,500.
- Actual expense method (IRS Form 8829). Multiply business-use percentage by your actual home costs: rent or mortgage interest, utilities, insurance, and repairs. California recognises this method, so CA state income tax savings are included.
Scope and limitations
Excluded: Excludes California SDI (State Disability Insurance, ~0.9% of gross wages, withheld separately by EDD). Figures use the 2025 FTB bracket schedules as the best available proxy for 2026 withholding; the FTB may publish updated 2026 thresholds that differ slightly. This calculator models a single Schedule C filer with no other income. It excludes home depreciation recapture, the 20% QBI deduction, health insurance deductions, and tax credits. Consult a tax professional before filing.
Data sources: Federal figures from IRS Rev. Proc. 2013-13, IRS Publication 587, and IRS Rev. Proc. 2025-32. California income tax figures verified against the California Department of Revenue for Tax Year 2026.
Sources
- IRS Rev. Proc. 2013-13 — Simplified Method ($5/sqft, 300 sqft max)
- IRS Publication 587 — Business Use of Your Home
- IRS Form 8829 Instructions — Actual Expense Method
- IRS Rev. Proc. 2025-32 — 2026 Standard Deduction Amounts
- California FTB — 2025 Form 540 Tax Rate Schedules (X, Y1, Y2, Z)
- California EDD — 2026 Withholding Schedules Method B (DE 44)
- Tax Foundation — California Income Tax Rates 2026
Frequently asked questions
Does California conform to the home office deduction?+
Yes. California generally conforms to federal Schedule C treatment. Both the simplified method ($5/sqft) and the actual expense method reduce your California AGI and therefore your California taxable income. For a single filer in the 9.3% bracket, a $1,500 simplified deduction saves roughly $130 in California income tax in addition to the federal savings.
What is California's income tax rate on home office savings?+
California has nine income tax brackets ranging from 1% to 12.3%, plus a 1% Mental Health Services surtax above $1,000,000. For most self-employed people earning $60,000 to $100,000 net profit, the marginal CA rate is 9.3%. The home office deduction reduces CA taxable income (federal AGI minus the $5,706 single or $11,412 MFJ CA standard deduction) at that marginal rate.
What is the home office deduction?+
The home office deduction (IRC §280A) lets self-employed people deduct the cost of a dedicated workspace in their home. The space must be used regularly and exclusively for business. The deduction is taken on Schedule C, which reduces net self-employment profit and therefore lowers SE tax, federal income tax, and most state income taxes.
What is the simplified method?+
The IRS simplified method (Rev. Proc. 2013-13) lets you deduct $5 per square foot of your home office, up to 300 square feet, for a maximum annual deduction of $1,500. No receipts, depreciation schedules, or Form 8829 are needed. The $5/sqft rate is statutory and has not changed since 2013.
What is the actual expense method?+
The actual method computes your business-use percentage (office sqft divided by total home sqft) and applies it to your actual home costs: rent or mortgage interest, utilities, insurance, and repairs. You claim this on IRS Form 8829. The actual method often yields a larger deduction than the simplified method for those with high home expenses.
Does the home office deduction reduce self-employment tax?+
Yes. The deduction is claimed on Schedule C, which reduces net profit before SE tax is calculated. Because SE tax is 15.3% on 92.35% of net profit, a $1,500 deduction saves roughly $212 in SE tax at any income level below the Social Security wage base ($184,500 for 2026).
What qualifies as a home office?+
The space must be used regularly and exclusively for business (IRC §280A(c)(1)). A dedicated room or partitioned area qualifies. It cannot double as a personal space or guest room. You do not have to use it every day, but it must be your principal place of business or a place where you regularly meet clients.
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