To deduct a home office, the space must be used exclusively and regularly as your principal place of business (or for meeting clients, or as a separate structure). The simplified method pays $5 per square foot up to 300 square feet ($1,500 max); the actual-expense method apportions real costs and often yields more.

What does "regular and exclusive use" actually mean?

These are two separate tests, and you have to pass both at the same time.

Exclusive use means the space is used only for business. Not mostly for business. Only. A dedicated room where you work is the clean case. A guest room that doubles as an office on some days fails, because the room is used for personal purposes. The qualifying area does not have to be a whole room: a separately identifiable space works, and it does not need a permanent partition, but that specific area must be used only for business.

Regular use means you use the space consistently for business, not occasionally or incidentally. Using a dedicated office only a few days a month, incidentally, is not regular use. (A kitchen table fails anyway, on exclusive use.) The IRS evaluates regularity on the facts, but the pattern has to show real, ongoing business use.

Both tests apply identically under either method. The simplified option changes the math, not the eligibility rules. (IRS, Simplified Option for Home Office Deduction)

What counts as a qualifying business purpose?

Passing regular and exclusive use is not enough on its own. The space also has to serve one of three purposes in IRC 280A(c)(1):

1. Your principal place of business. This includes a place you use for the administrative or management activities of your trade or business, as long as you have no other fixed location where you conduct substantial administrative or management activities. Billing clients, keeping books, ordering supplies, scheduling work: if the home office is where the business is actually run, it qualifies even if you also work on-site elsewhere.

2. Meeting clients, patients, or customers. A space you use to meet or deal with clients in the normal course of business qualifies.

3. A separate structure. A detached garage, studio, or shed used in connection with your business qualifies under a looser purpose test than the inside of the house (it does not have to be your principal place of business or a place where you meet clients). The regular-and-exclusive-use requirement still applies.

Two exceptions relax the exclusive-use test. A licensed or certified daycare can deduct part of the cost of space that is also used personally, prorated by the hours the space is used for daycare (IRC 280A(c)(4)). Space used regularly to store inventory or product samples can also qualify if you sell products at retail or wholesale and your home is the business's only fixed location (IRC 280A(c)(2)). (IRC §280A)

Which method should you use: simplified or actual expenses?

You choose one method per tax year on your timely filed original return, and you cannot switch methods for that year after the fact. Here is how they compare.

Rule of thumb: if 300 square feet at $5 ($1,500) covers your real cost, take the simplified method and skip the bookkeeping. If apportioned actual costs clearly exceed $1,500, the actual-expense method usually wins. The tradeoff is depreciation recapture: depreciation claimed on the business portion is taxed when you sell, clawing back part of the benefit.

One more limit for both methods: the deduction cannot exceed the gross income from the business use of the home minus your other business expenses that are not related to the home, so it cannot create or increase a business loss. Under the actual method the unused amount carries forward; under the simplified method it is lost. (IRS, Simplified Option for Home Office Deduction)

How does the home office deduction work if you own an S-corp?

This is where most S-corp owners get it wrong. As an owner-employee of your S-corp, you are an employee for tax purposes. Since the One Big Beautiful Bill Act made the suspension of miscellaneous itemized deductions permanent (IRC 67(h)), employees cannot deduct unreimbursed business expenses, including home office costs. So you cannot take the home office deduction directly on your personal return.

The correct route is an accountable plan: the corporation reimburses you for the business use of your home, and the reimbursement is excluded from your wages while the corporation deducts it as an ordinary business expense. Because you are an employee, the home office must also be for the convenience of the corporation, not just for your own convenience (IRC 280A(c)(1)). To qualify as an accountable plan under Treasury Regulation 1.62-2, the arrangement must meet three requirements:

1. Business connection. The reimbursement covers expenses you incurred performing services as an employee.

2. Substantiation. You account for the expenses to the corporation within a reasonable time. The regulation's safe harbor treats substantiation within 60 days after the expense was paid or incurred as reasonable.

3. Return of excess. You return any amount paid in excess of substantiated expenses within a reasonable time. The safe harbor is 120 days.

(Treas. Reg. §1.62-2)

In practice: the S-corp adopts a written accountable plan, you submit the home office calculation with the underlying receipts, the corporation reimburses you, and the reimbursement stays off your W-2. If the reimbursement includes a share of mortgage interest or property taxes, deduct only the unreimbursed remainder on Schedule A so the same dollars are not deducted twice. If the arrangement itself fails any of the three requirements, all payments under it are treated as wages, subject to income and payroll tax. If the plan qualifies but you fail to substantiate or return a particular excess amount, only that unsubstantiated or unreturned amount is treated as wages.

What disqualifies most people?

• The guest-room office. Occasional business use of a room that also serves personal purposes fails exclusive use. This is the single most common home office failure we see.

• **Being a W-2 employee. Employees generally cannot deduct a home office or other unreimbursed employee expenses; the suspension that started in 2018 was made permanent by the One Big Beautiful Bill Act (IRC 67(h)). Narrow statutory exceptions exist (for example, Armed Forces reservists, qualified performing artists and fee-basis government officials), and an employee who also runs a side business can still claim a home office for that business.

• No qualifying business purpose. A beautiful, exclusive, regularly used office still fails if it is not your principal place of business, a client-meeting space, or a separate structure.

• Double-dipping under the simplified method. If you itemize, home-related itemized deductions (mortgage interest, real estate taxes) stay on Schedule A, subject to the normal limits such as the SALT cap and the mortgage-debt limit; do not also apportion them to the business. Under the actual-expense method, the business share of those costs moves to Schedule C instead, where the SALT cap does not apply.

• Creating a loss. Neither method lets the home office deduction exceed the business income it is tied to.

Pending review by Brian Thomas, EA. Updated September 25, 2026.

This article is free educational content, not tax advice for your specific situation. If you want a plan built around your actual numbers, that is what our paid tax planning engagements do.