Eligibility: The Regular and Exclusive Use Test
To claim the home office deduction, you must use a portion of your home regularly and exclusively for business purposes. 'Regularly' means consistent ongoing use (a few hours a week consistently, not occasional use). 'Exclusively' means that space is used ONLY for business — not also as a guest bedroom, kids' homework area, or for any personal purpose.
The exclusive use is strict. A converted garage that's 100% your office? Qualifies. A guest bedroom you also work in occasionally? Doesn't qualify. The kitchen table where you work in the morning and eat dinner in the evening? Doesn't qualify. The IRS specifically tests this through field audits, taking photos and asking questions.
W-2 employees CANNOT claim the home office deduction. The Tax Cuts and Jobs Act eliminated unreimbursed employee business expense deductions starting 2018, including the home office. Even if you work from home full-time as a W-2 employee, you cannot deduct your home office.
Self-employed individuals (Schedule C filers, partners, S-corp shareholders working from home) CAN claim the deduction. S-corp owners use a slightly different mechanism: an 'accountable plan' reimbursement from the corporation to the owner, which is deductible to the corporation and tax-free to the owner.
Principal place of business test: in addition to regular and exclusive use, the home office must be your principal place of business OR a place where you meet clients/customers regularly OR a separate structure used only for business. Most self-employed people meet the principal place of business test.
Simplified Method ($5/sq ft, max $1,500)
The simplified method gives you $5 per square foot of qualified office space, up to 300 square feet. Maximum deduction: $1,500. You don't need to track actual home expenses or worry about depreciation.
Calculation: 200 sq ft × $5 = $1,000. That's your deduction. Done. No recordkeeping required beyond documenting the office square footage.
Pros: easy, no depreciation recapture at home sale, no risk of recordkeeping audit issues. The simplified method is the right choice for: small home offices (under 200 sq ft), people who don't track home expenses carefully, or anyone who wants to minimize tax-prep complexity.
Cons: capped at $1,500 even if your actual proportional expenses are $5,000+. For a 250 sq ft office in a $40,000/year all-in home cost, you're leaving $3,500+ of deduction on the table.
When to use simplified: if your office is small (under 150 sq ft), if you rent and don't have many home expenses, or if you simply don't want to track receipts and calculations all year. Many self-employed people who could deduct $4,000+ choose the simplified $1,500 just to avoid the paperwork.
Regular Method (Proportional Actual Expenses)
The regular method calculates your business-use percentage of the home (e.g., 200 sq ft office in a 2,000 sq ft home = 10%) and applies that percentage to actual home expenses.
Deductible home expenses include: mortgage interest, property tax, utilities (electricity, gas, water, sewer), homeowners insurance, depreciation, repairs (allocated as direct or indirect), and HOA fees.
Concrete calculation for 10% business use: $30,000 mortgage interest + $8,000 property tax + $4,000 utilities + $1,500 insurance + $2,500 depreciation + $1,000 repairs = $47,000 total home expenses. 10% = $4,700 deduction. Vs. simplified method maximum of $1,500 — the regular method gets 3x more.
Direct vs indirect expenses: direct expenses (paint for the office, repair to the office only) are 100% deductible. Indirect expenses (utilities, insurance, depreciation across the whole home) are deductible at the business-use percentage.
Renters: don't have mortgage interest or property tax, but rent is fully proportional. 10% business use of $36,000/year rent = $3,600 deduction. Plus utilities, insurance, etc. The regular method works equally well for renters.
Depreciation Recapture: The Trap
If you use the regular method and depreciate the business portion of your home, you'll face depreciation recapture when you eventually sell. The accumulated depreciation is taxed at a special 25% federal rate (Section 1250 recapture) on sale.
Concrete example: $400,000 home, 10% business use, $40,000 of business basis. Depreciation over 39 years (commercial) = ~$1,026/year. Over 10 years of business use, accumulated depreciation $10,260. At sale, $10,260 of gain is recaptured at 25% = $2,565 of additional tax.
The simplified method does NOT trigger recapture. This is one reason the simplified method is sometimes preferred even when the regular method would yield larger annual deductions.
Section 121 primary residence exclusion still applies to the non-business portion. If you sell at a $200K gain, $20K (10%) is allocable to the business portion (subject to depreciation recapture and capital gains), and $180K (90%) is allocable to personal residence (eligible for $250K/$500K exclusion).
Strategic implication: if you plan to sell your home within 5-10 years and the office hasn't generated huge regular method deductions, the simplified method might be net-better despite the lower annual deduction. Run the math on the cumulative deduction value vs. the recapture tax at sale.
Common Mistakes
Failing the exclusive use test. The most common audit issue. Personal use of the office space — even occasional — disqualifies the deduction. Document the office's exclusive use with photos, a desk and computer setup that's clearly business, and physical separation from personal areas.
Wrong percentage calculation. Some people use the percentage of total rooms (e.g., 1 room out of 8). This is allowable but typically yields a smaller percentage than square footage. Use square footage when possible — it's the IRS-preferred method and usually larger.
Including non-deductible expenses. Personal items, food, and luxury home features aren't deductible at any percentage. Don't try to deduct your kitchen renovation as a 'home expense' just because some percentage of your home is the office.
Forgetting depreciation when calculating. The regular method requires depreciation deduction on the business portion of the home. Skipping depreciation forfeits the deduction. But when you sell, the IRS calculates recapture on 'allowable' depreciation — meaning you owe recapture even on depreciation you didn't actually take. Always take the depreciation if using the regular method.
S-corp employee mistake. S-corp owners can't take the home office deduction directly on their personal return (the corporation has to reimburse them through an accountable plan). Setting up the accountable plan correctly requires written documentation. Many S-corp owners miss this opportunity.
Not adjusting when business changes. If your business activity changes (you start or stop using a portion of your home for business), the deduction changes. Keep documentation of when changes occurred and use proportional calculations for partial-year periods.