Eligibility in 60 Seconds

  • Exclusive + regular business use.
  • Principal place, client meeting, or inventory storage.
  • S-corp: reimburse via accountable plan; do not deduct personally.

Pair with Tax Deductions, S-Corp, Year-End Planning, and Estimated Taxes.

Method Math

Method Calc Best for
Simplified $5 × sq ft to 300 = $1,500 max Small, renters, low records
Actual % × interest, taxes, utilities, repairs + depreciation Owners, large dedicated %

Model both; actual often 2-4x simplified for owners.

Documentation That Survives

  • Floor plan with measurements + photos annually.
  • Calendar showing regular use.
  • Bills, mortgage statements, repair invoices allocated by %.
  • Reimbursement report for S-corp — see Payroll and Month-End Close.

Retain per Record Retention and Audit Procedures.

Recapture Warning

Depreciated home-office portion triggers unrecaptured gain on sale. Factor into Filing Deadlines provision and Financial Analysis.

Worked Example: 240 Sq Ft Office in Owned Home

Home: 2,000 sq ft, office 240 sq ft (12%). Annual: mortgage interest $9,000, property tax $4,000, utilities $3,600, insurance $1,400, repairs (whole-home) $2,000; depreciation on office portion $1,800.

Method Math Deduction
Simplified 240 × $5 $1,200
Actual 12% × ($9,000+$4,000+$3,600+$1,400+$2,000) + $1,800 $2,400 + $1,800 = $4,200

Actual wins by $3,000 — 3.5× simplified. The gap widens with higher rates, bigger offices, and repair years. Renters see similar multiples: 12% of $24,000 rent + utilities ≈ $3,300+ vs $1,200 simplified. Model both every year; the right answer flips with repairs and rate moves.

Exclusive-Use Traps (Where Claims Die)

  • The guest-bedroom office. Beds, TVs, and kids’ homework in the “exclusive” room fail the test on photos alone. Exclusive means exclusive — a curtain divider doesn’t create it.
  • Kitchen-table entrepreneurship. Regular use of a non-exclusive area doesn’t qualify, no matter how many hours. The 300-sq-ft simplified claim on an open-plan living room is audit bait.
  • No principal-place analysis. If you also rent a coworking desk where you do admin work, the home office may not be the principal place. Document where management and admin actually happen — calendar + lease comparison.
  • Inventory exception (use it). Storing product samples or inventory in the garage/basement qualifies under a separate, easier test — no exclusive-office needed. Photograph the storage area with labels.

Each trap is a documentation problem with a documentation fix: dated photos, floor plan with measurements, and a one-paragraph use memo filed with the return workpapers — see Year-End Planning.

S-Corp Accountable Plan Mechanics

S-corp owners cannot take the home-office deduction on Schedule A (suspended post-TCJA) — the corporation reimburses the owner instead, under an accountable plan adopted in board minutes:

  1. Compute the actual-method amount (simplified can’t be reimbursed the same way — use actual costs).
  2. Submit monthly expense reports with receipts and the floor-plan percentage.
  3. Corporation deducts reimbursement as office expense; owner receives it tax-free (not wages, no payroll tax).

Miss a step and the economics collapse: unreimbursed costs are nondeductible personal expenses, while sloppy reimbursements get reclassified as wages (income + payroll tax). Set the plan up before year-end with Payroll coding the reimbursements outside W-2 Boxes 1/3/5.

FAQ

Can we switch methods yearly?

Yes. Choose annually; simplified in low-expense years, actual when repairs or rates spike.

What about internet and phone?

Direct business portion with bills and log; do not double-count personal.

Next Steps

  1. Measure, photo, and file floor plan now.
  2. Model both methods on 2026 actuals.
  3. Set S-corp reimbursement before year-end.