Who can claim a home office, and what the two methods do
The home office deduction is available to self-employed people — sole traders, partners, and single-member LLC owners filing Schedule C. Employees cannot claim it on a federal return, because the miscellaneous itemised deduction that once allowed it was suspended in 2018. Working from home for an employer therefore gives you no federal deduction, whatever your employer's policy says.
Two tests gate the deduction under IRC §280A. The space must be used regularly — occasional use does not count — and exclusively for business. Exclusive is strict: a spare room that doubles as a guest bedroom fails, and a corner of the living room fails unless it is genuinely set aside. Two exceptions exist: storage of inventory or product samples, and a licensed daycare facility, both of which allow mixed use.
The space must also be your principal place of business, or a place you meet clients regularly, or a separate structure. Administrative work counts: if you do your billing, scheduling and record-keeping at home and have no other fixed office, the home qualifies even when the paid work happens on client sites.
Given a qualifying space, you then choose a method. The simplified method is a flat $5 per square foot on up to 300 square feet, capped at $1,500. The regular method allocates real costs by floor area and has no ceiling. The choice is made year by year, so you can use the simplified method one year and Form 8829 the next.
The arithmetic of each method
Business use percentage. Office area divided by total home area. Floor area is the usual measure; the IRS also accepts a room count when the rooms are of roughly equal size, but area is more defensible and usually more favourable to a small office.
Regular method. Direct expenses — costs that benefit only the office, such as painting that room — are deducted in full. Indirect expenses that cover the whole home are multiplied by the business use percentage: rent or mortgage interest, utilities, homeowners or renters insurance, property tax, and general repairs. Homeowners add depreciation on the business share of the building, computed over 39 years as nonresidential real property. Expenses that benefit no part of the office, such as landscaping or a new bathroom, are not deductible at all.
Simplified method. Multiply the smaller of your office area and 300 square feet by $5. That is the entire calculation. It replaces every actual expense — you deduct no share of rent, no utilities, no insurance, and no depreciation. Mortgage interest and property tax remain fully deductible on Schedule A if you itemise, which the regular method would otherwise split between Schedule A and Form 8829.
The gross income limit applies to both. The deduction cannot exceed the net income of the business that uses the home, computed before this deduction. The difference is what happens to the excess: under the regular method it carries forward indefinitely to a year with enough income; under the simplified method it is lost permanently, and a carryover from an earlier regular-method year cannot be used in a simplified-method year.
Worked example: a 150 sq ft office in an 1,800 sq ft home
A freelance designer works from a dedicated 150 square foot room in an 1,800 square foot rented flat. Rent is $18,000 a year, utilities $3,600, renters insurance and any local property charges $2,800. She spent $500 repainting the office. Her business earned $45,000 before this deduction.
- Business use percentage. 150 ÷ 1,800 = 0.083333, or 8.3333 percent.
- Indirect expenses. 18,000 + 3,600 + 2,800 = $24,400.
- Allocated share. 24,400 × 0.083333 = $2,033.33.
- Direct expenses. The $500 of painting is deducted in full.
- Regular method total. 2,033.33 + 500 = $2,533.33.
- Simplified method. 150 × $5 = $750.00.
- Income limit. Business income of $45,000 is far above either figure, so neither is capped.
- Result. The regular method wins by 2,533.33 − 750 = $1,783.33.
Price the difference. Because the deduction reduces Schedule C profit, it saves income tax at her marginal rate and self-employment tax at 14.13 percent of profit. At a 22 percent marginal rate the extra $1,783.33 saves 1,783.33 × 0.1413 = $251.98 of self-employment tax, and then (1,783.33 − 251.98 ÷ 2) × 0.22 = $364.61 of income tax, because half the self-employment tax saving is itself an adjustment — $616.59 of federal tax on one deduction. The self-employment tax calculator shows why business deductions are worth more than personal ones.
Now cut her business income to $1,000. The regular method total is unchanged at $2,533.33, but only $1,000 is allowed this year and $1,533.33 carries forward. The simplified figure of $750 would be fully allowed, but taking it would forfeit the carryover, so the regular method is still the better choice at $1,000 of income.
How to choose between the methods
The regular method usually wins on the numbers, and the margin grows with rent. The simplified method pays a flat $5 per square foot, which is $750 on a 150 square foot office. The regular method pays your actual costs times the same area fraction — in a high-rent city that fraction of $40,000 of housing costs is several thousand dollars. The break-even point is where your business use percentage applied to your indirect expenses equals $5 per square foot: for a 150 sq ft office at 8.3333 percent business use, that is $9,000 of annual indirect expenses, and the table below works through the range.
The simplified method wins on effort and on the sale of a home you own. No receipts, no depreciation schedule, no Form 8829, no allocation of every utility bill. And because it claims no depreciation, there is no unrecaptured section 1250 gain to pay tax on when you sell — depreciation claimed under the regular method is recaptured at up to 25 percent and is not sheltered by the section 121 principal residence exclusion.
The income limit changes the ranking at low profit. Both methods are capped at business net income, but only the regular method's excess survives. If your business is near break-even, the regular method preserves the disallowed amount for a future year while the simplified method throws it away.
Watch the interaction with Schedule A if you own and itemise. Under the regular method, the business share of mortgage interest and property tax moves from Schedule A to Form 8829. That is a real gain if the SALT cap is limiting your itemised deduction, because Form 8829 is not subject to it. Under the simplified method those amounts stay entirely on Schedule A.
Measure honestly and keep the evidence. A floor plan with the office marked, a photograph, and the basis for the total area are enough. The regular and exclusive use test is where these deductions are lost on audit, not the arithmetic.
Where the two methods break even
| Annual indirect expenses | Regular method | Simplified method | Larger method |
|---|---|---|---|
| $6,000 | $500.00 | $750.00 | Simplified, by $250.00 |
| $9,000 | $750.00 | $750.00 | Break-even |
| $12,000 | $1,000.00 | $750.00 | Regular, by $250.00 |
| $18,000 | $1,500.00 | $750.00 | Regular, by $750.00 |
| $24,400 | $2,033.33 | $750.00 | Regular, by $1,283.33 |
| $36,000 | $3,000.00 | $750.00 | Regular, by $2,250.00 |
| $48,000 | $4,000.00 | $750.00 | Regular, by $3,250.00 |
Every cell is produced by the same formulas the calculator uses. Direct expenses are excluded here so the two methods are compared on the same footing; adding any direct expense shifts the balance further toward the regular method, because the simplified method never deducts them.
Mistakes that lose the deduction or shrink it
- Claiming a space that is not used exclusively for business. A guest room with a desk fails the test. This is the most common reason the deduction is disallowed on examination.
- Claiming it as an employee. Unreimbursed employee expenses are not deductible federally through 2025 and beyond under current law. An accountable reimbursement plan from the employer is the alternative.
- Deducting mortgage principal. Only the interest portion is an indirect expense; principal repayments are not deductible at all.
- Including expenses that do not benefit the office. Lawn care, a swimming pool and a kitchen remodel are unrelated expenses and are excluded even in part.
- Forgetting the income limit. The deduction cannot create or increase a business loss. Enter net income before the home office deduction, not gross receipts.
- Overlooking depreciation recapture. Claiming depreciation is right when the numbers support it, but the IRS treats depreciation as allowed-or-allowable on sale — declining to claim it does not avoid the recapture.
- Measuring only the desk. The deduction is based on the area used for business, which for a dedicated room is the whole room.
Depreciation is recaptured whether or not you claimed it
When you sell a home in which you claimed a home office under the regular method, the depreciation you took on the business portion is recaptured as unrecaptured section 1250 gain and taxed at up to 25 percent. The section 121 exclusion of $250,000 of gain, or $500,000 on a joint return, does not shelter it. The trap is the phrase allowed or allowable: the recapture is computed on the depreciation you were entitled to claim, so simply not claiming it does not avoid the tax. The simplified method is the clean way out — it claims no depreciation at all, so there is nothing to recapture for those years.
Related deductions and where the figures go
The home office deduction lands on Schedule C, so it reduces net profit and therefore both income tax and self-employment tax. Feed the resulting profit into the self-employment tax calculator and then into the quarterly estimated tax calculator to resize your instalments; a $2,500 deduction typically moves a quarterly payment by $200 or more.
The same logic applies to vehicle costs. If your home office is your principal place of business, trips from home to a client site are business miles rather than non-deductible commuting — which is one of the largest indirect benefits of qualifying for this deduction. Size it with the business mileage deduction calculator.
Equipment used in the office is separate. A computer, desk or monitor is a business asset deducted through section 179 expensing, bonus depreciation, or the de minimis safe harbour, not through the home office calculation. The MACRS depreciation calculator handles assets that are capitalised rather than expensed.
Finally, remember that the deduction's value depends on the profit it shelters. Build the whole picture with the taxable income calculator, and if you own a home, keep a record of every year's depreciation so the eventual recapture computation is a lookup rather than a reconstruction.