Home Office Deduction Calculator
Simplified versus regular home office deduction with winner from sqft and expenses.
What it does
The home office deduction offers two doors: simplified at $5 per square foot up to 300, or regular prorating real expenses by floor share. One rewards big offices simply, the other rewards expensive homes precisely.
The tool above takes office size with yearly home expenses and whole home size. It returns both methods with the winning margin beside them.
The default of 150 ft2 in a 1,500 ft2 home with $12,000 expenses gives $750.00 simplified against $1,200.00 regular: regular wins by $450.00. A 350 ft2 office caps simplified at $1,500.00.
The methods follow IRS home office guidance with the simplified option rules matching each cap. Both require regular exclusive business use; employees generally cannot claim it.
How to use
- Measure the exclusive office area in ft2.
- Total a year of home expenses.
- Enter the whole home size in ft2.
- Read both methods side by side.
- Take the winner, keeping exclusive use proof.
Formula
- $5
- Simplified rate per square foot.
- 300
- Simplified cap in ft2 ($1,500 max).
- share
- Office over home floor fraction.
Exclusive regular use required: guest rooms and kitchen tables fail. Simplified skips depreciation recapture later; regular tracks it for the eventual sale.
Worked example
Example: 150 ft2, $12,000 expenses, 1,500 ft2 home
Defaults: sqft 150, expenses 12000, home 1500.
- Simplified: 150 x $5 = $750.00 (under the 300 cap).
- Share: 150 / 1,500 = 10%.
- Regular: 12,000 x 10% = $1,200.00.
- Winner: regular by 1,200 - 750 = $450.00.
- Tool shows $750.00, $1,200.00, Regular wins by $450.00.
Reference table
| Office / expenses / home | Simplified | Regular |
|---|---|---|
| 150 ft2 / $12,000 / 1,500 | $750.00 | $1,200.00 |
| 350 ft2 / $12,000 / 1,500 | $1,500.00 | $2,800.00 |
| 100 ft2 / $6,000 / 2,000 | $500.00 | $300.00 |
Limits
- Exclusive regular use required, strictly enforced.
- Employees generally ineligible since 2018.
- Simplified skips depreciation but caps low.
- State rules can differ from federal.
Common mistakes
- Claiming shared living spaces as offices.
- Forgetting the 300 ft2 simplified cap.
- Skipping the regular math that often wins.
- Missing expense records the regular method needs.
- Ignoring depreciation recapture at sale.
Try it yourself
Quick checks. Answers sit tucked under each question.
350 ft2 office?
Simplified caps at 300 x $5 = $1,500.00.
100 ft2, $6,000 expenses, 2,000 home?
Simplified $500.00 beats regular $300.00 by $200.00.
Guest bedroom office?
Fails exclusive use: no deduction either method.
Questions
Simplified or regular?
Run both. Simplified is $5/ft2 to 300; regular prorates real expenses. Take the larger.
What is the max simplified?
$1,500: 300 ft2 times $5.
Can employees claim it?
Generally no since 2018. Self-employed and qualifying business owners can.
What counts as exclusive?
Space used only for business, regularly. Dual use rooms fail.
Renters too?
Yes. Rent share prorates under the regular method like mortgage interest does.
Depreciation trap?
Regular method depreciates the office share, recaptured at sale. Simplified avoids it.