Two methods, one winner — and it depends on your situation

The IRS offers two ways to calculate your home office deduction. Most people pick the simplified method because it's easier. That's fine when it wins, but for renters in high-cost cities or homeowners with large utility bills, the actual expense method can produce a deduction that's three to four times larger.

The simplified method

$5 per square foot, up to 300 square feet, for a maximum deduction of $1,500. That's the whole calculation. No Form 8829, no recordkeeping beyond your office dimensions. The cap makes this method lose badly for anyone with a large, expensive dedicated space.

The actual expense method

You calculate the business-use percentage of your home (office square footage divided by total home square footage), then apply that percentage to your qualifying expenses: rent or mortgage interest, utilities, homeowners insurance, and repairs. If your office is 200 sq ft out of 1,000 sq ft total, 20% of every qualifying dollar is deductible. A renter paying $24,000/year with $6,000 in utilities gets a $6,000 deduction on the actual method vs. $1,000 on simplified.

The catch: actual method requires Form 8829, and the deduction can't exceed your net business income. If you had a rough year, you can't use a home office deduction to create or increase a loss. Unused deductions can be carried forward, but simplified deductions cannot.

The "exclusive and regular use" test

Both methods require the same IRS standard: the space must be used exclusively and regularly for business, and it must be your principal place of business or a place where you meet clients. The guest bedroom that doubles as your office doesn't qualify. A dedicated room with a desk, shelving, and nothing else does. If you're ever audited, the physical separation matters.

What to include as expenses

Renters: include monthly rent. Homeowners: include mortgage interest (not principal), real estate taxes, and homeowners insurance — not the full mortgage payment. Both: utilities (electricity, gas, water), internet (usually allocated separately at 100% business use), and home repairs that benefit the whole house proportionally. Internet is almost always better claimed as a direct business expense at full cost rather than running it through the home office business-use percentage.

Results are estimates. The actual expense method requires Form 8829. Home office deductions cannot exceed net business income for the year. Consult a tax professional before claiming.