Home Office Deduction Calculator: Simplified $5 per Sq Ft vs Regular Method
Estimate your home office deduction with the IRS simplified method ($5 per square foot, up to 300 sq ft, $1,500 max) or the regular actual-expense method (business share of rent, mortgage interest, taxes, utilities, insurance, repairs and 39-year depreciation), with partial-year use, the gross income limit, carryover and the tax it saves.
How it works
Simplified: deduction = min(office sq ft, 300) × months used ÷ 12 × $5, capped at business income − other business expenses (max $1,500) · Regular: business % = office sq ft ÷ home sq ft; deduction = business % × (mortgage interest + real estate taxes) + business % × (rent + insurance + utilities + repairs) + business % × home basis excluding land × 2.564% (first year: Table 2 rate), with operating costs and depreciation limited by income and carried over · Tax saved ≈ deduction × marginal rate
If you are self-employed and use part of your home regularly and exclusively for business, you can deduct a home office in one of two ways each year. The simplified method allows $5 per square foot for up to 300 square feet, a maximum of $1,500. If the office was used for only part of the year, the IRS averages the square footage over 12 months, counting only months with at least 15 days of business use. It needs no expense records, involves no depreciation, and itemizers keep their full mortgage interest and real estate taxes on Schedule A. The regular method (Form 8829) deducts your actual costs times the business-use percentage, usually the office area divided by the home area. Mortgage interest and real estate taxes come first. Then come operating costs such as rent, insurance, utilities and repairs. Depreciation comes last: the business part of the home’s basis (excluding land) is depreciated over 39 years, 2.564% a year, or a smaller first-year rate based on the month you started. Both methods are limited to business income minus your other business expenses. Under the regular method the excess carries forward to next year; under the simplified method it is lost. Repairs that affect only the office (painting the office, for example) are fully deductible under the regular method and are not included here. Pick whichever method gives the larger deduction. You can switch methods from year to year. Tax saved is an estimate: deduction × your combined marginal rate, which for the self-employed includes about 14.1% self-employment tax.
Worked example
With the default inputs, a 150 sq ft office used all 12 months counts as min(150, 300) × 12 ÷ 12 = 150 sq ft. The simplified deduction is 150 × $5 = $750. Business income of $60,000 minus $15,000 of other expenses leaves a $45,000 limit, so nothing is capped. At a 25% combined marginal rate, the deduction saves about $750 × 25% = $187.50. Switch to Compare both and the 2,000 sq ft home gives a 7.5% business share. Mortgage interest and taxes of $12,500 contribute $937.50, insurance, utilities and repairs of $5,600 contribute $420.00, and depreciation of $300,000 × 7.5% × 2.564% adds $576.90. That makes a regular deduction of $1,934.40, larger than the $750 simplified figure, saving about $483.60.
Sources: IRS: Simplified option for home office deduction · IRS Publication 587 (2025), Business Use of Your Home · Keeper: Home office deduction calculator and examples · US Tax Tools: Home office deduction calculator
Frequently asked questions
How much is the simplified home office deduction?
$5 per square foot of office space, up to 300 square feet, so at most $1,500 a year. If the office was used only part of the year, average the square footage over 12 months, counting only months with at least 15 days of business use.
Is the simplified or regular method better?
The regular method usually wins when the office is a large share of the home or housing costs are high, because it deducts real rent, utilities and depreciation with no 300 sq ft cap. The simplified method wins on simplicity and avoids depreciation recapture when you sell. You can choose either method each year.
What does "regular and exclusive use" mean?
The space must be used only for business and on a continuing basis. A spare room used solely as your office qualifies; a guest room or the kitchen table that doubles as a workspace does not. Daycare providers and inventory storage have special exceptions.
Can W-2 employees claim the home office deduction?
Not on their federal return. Since 2018 unreimbursed employee expenses, including a home office, are not deductible for employees. The deduction is for the self-employed, partners and other business owners.
What if my business has little income?
Both methods are limited to business income minus your other business expenses, so the deduction cannot create a loss. Under the regular method the unused amount carries forward to future years; under the simplified method it is lost.
Do renters get a home office deduction?
Yes. Under the regular method a renter deducts the business share of rent, renters insurance and utilities. For example, a 100 sq ft office in a 900 sq ft apartment with $800 a month rent is 11.1% of $9,600, or about $1,067 a year of rent alone.
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Educational estimate using simplified US federal rules. It ignores state tax, daycare and storage rules, direct office-only expenses and your full situation. Not tax advice; confirm with IRS Publication 587 or a tax professional.