Home office deduction audit: proving the space qualifies

Where you stand

A letter asking about your home office usually names the deduction line and asks you to substantiate it. That is a request for documents, not a conclusion. Start by deciding which calculation method you used, because the records you need depend on it.

Two methods, one basic test

The IRS describes a simplified option that multiplies a set rate by the square footage of the home used for business, with a cap on the number of square feet. The rate and cap are time-sensitive, so check the IRS page for the current figures. The regular method, covered in IRS Publication 587, calculates actual expenses. The IRS page for the simplified method says both methods require that part of the home be used exclusively and regularly for business, and that the simplified method changes how the deduction is calculated, not who qualifies.

• Exclusive use: the space is used only for business
• Regular use: the space is used on an ongoing basis, not occasionally
• Simplified method: square footage drives the calculation
• Regular method: actual household expenses, allocated to the business space

Example: remote bookkeeper in a spare bedroom

Consider a bookkeeper who works for several clients from a spare bedroom. The room holds a desk, shelving for client files and a printer, and nothing else. Useful records would include a simple floor plan with measurements, dated photos, a client list showing work performed there, and the lease or mortgage statement showing the home's total size.

Contrast this with a guest room where a desk sits beside a daybed. The examiner is likely to ask how the room is used when no work is happening. Be ready to answer honestly, because the exclusivity requirement is the point most often tested.

Records to gather

If you used the simplified method, you mainly need to prove the square footage and the business use. If you used the regular method, you also need the household bills for the year and a clear way you split them.

• Measurements of the business space and the whole home
• Photos of the space as it is used
• Utility, insurance, and mortgage interest or rent records, if you used the regular method
• Evidence that your business relies on the space, such as client records or a lease clause

What not to do

Do not claim more square footage than you measured. Do not describe the space as exclusive if family members or guests use it. Do not guess at expenses; use statements. If you realize you made a mistake, say so in your response and ask a qualified practitioner how to correct it.

Who can help

Many people answer a home office question on their own, because the records are few. If your situation involves a business owner, shared spaces, or multiple years, you may want an attorney, CPA or enrolled agent to review before you send.

How a written response fits

IRS Audit Defense Pro is software that helps you organize your facts and draft a response letter you review and send yourself; it is not a law firm, CPA or enrolled agent. For this deduction, a short letter that states the method you used, the measurements, how the space is used and what is enclosed is usually enough structure for a reviewer to follow. See Publication 587 for the rules on business use of your home.

Frequently asked questions

Sources

• IRS: Simplified option for home office deduction
• IRS Publication 587: Business Use of Your Home
• IRS Publication 583: Starting a Business and Keeping Records

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