The Consultant's Home Office: Simplified or Regular Method, the Principal-Place-of-Business Rule, and the Client-Site Mileage It Unlocks

The consultant's home office is small as a deduction and large as a gateway, and the gateway is the principal-place-of-business rule. The test: a portion of the home used regularly and exclusively for the business — a room, or a clearly defined area, used for nothing else (the guest room with a desk fails; the converted bedroom used only for the practice passes) — and used as the principal place of business, which for a consultant who works at clients' sites is met under the administrative-or-management rule (the contractor home-office guide covers the same kitchen-table rule): the home is the principal place of business if the consultant uses it for the administrative or management activities of the practice (billing, scheduling, proposals, bookkeeping, research, client communication) and there is no other fixed location where the consultant conducts substantial administrative or management activities — a consultant at a client's site four days a week who does the practice's administration from the home office qualifies, because the client's site is the client's location, not the consultant's fixed place of business; a consultant who rents a coworking desk and does the administration there has a competing fixed location, and the home office's principal-place status depends on where the substantial administrative work actually happens. The two methods. Simplified: a prescribed rate of US$5 per square foot times the office's square footage, capped at 300 square feet (a US$1,500 maximum) — no depreciation, no recapture at sale, no allocation of actual costs, mortgage interest and property taxes fully on Schedule A — the method for a small office, a home the consultant expects to sell, or a consultant who wants ten minutes of paperwork. Regular: the business-use percentage (the office's square footage over the home's total) applied to the home's actual costs — mortgage interest, property taxes, insurance, utilities, repairs, and depreciation of the home's business share (over thirty-nine years for the business portion) — plus the office's direct costs in full; larger for a bigger office in a higher-cost home, with the gross income limitation (the deduction can't exceed the practice's net income before home costs, with the excess carried forward — rarely binding for a profitable consultant) and the recapture consequence: the depreciation taken on the business portion is recaptured at sale (taxed at the unrecaptured section 1250 rate up to 25%, even within the section 121 exclusion), so a consultant who takes US$1,200 a year of home depreciation for ten years has US$12,000 of recapture when the home sells — a real number, and one the method choice is made with: the regular method for a long-held home where the annual deduction is materially larger; the simplified method where the home may sell within a few years or the difference is small. The mileage — the gateway: with the home office as the principal place of business, every trip from home to a client site, between clients, to the airport for an engagement, and home again is business travel (deductible at the standard mileage rate or under the actual-expense method — the vehicle method chosen in the vehicle's first business year, with the log as the substantiation); without it, the drive to the first client and home from the last is a nondeductible commute — and for a consultant driving 12,000 miles a year to clients, the reclassification is worth several thousand dollars annually, roughly ten times the simplified office deduction. The S corporation consultant's version (the consulting entity guide): the corporation cannot deduct the shareholder's home expenses directly — the consultant is reimbursed under an accountable plan for the business use of the home (the same regular-method computation, documented, reimbursed monthly or quarterly; the reimbursement deductible to the corporation and tax-free to the shareholder), and the mileage is reimbursed the same way (the accountable plan's mileage log and reimbursement at the standard rate) — the consultant who elected S status and stopped claiming the home office because "Form 8829 doesn't apply" has forfeited the deduction that an accountable plan preserves. The renter's version: a consultant who rents applies the business-use percentage to the rent, utilities, and renter's insurance under the regular method (no depreciation, no recapture) or uses the simplified method — with the rent's share often making the regular method the larger deduction for a renter in a high-rent market. The travel interaction: a consultant on an extended out-of-town engagement (weeks at a client's city, lodging away from home) has the tax home question — the home office's city is the tax home if the practice's principal place of business is there, and the engagement's lodging and per diem are deductible travel away from home; a consultant whose engagement runs past a year in one location may have shifted the tax home to that location under the one-year rule, converting the lodging and meals into nondeductible personal costs — the extended-engagement consultant watches the calendar. The equipment in the office: the desk, chair, monitors, and the office's furnishings are business property (expensed under the de minimis election or section 179, in full if used only for the business) — separate from the home's costs and not at the business-use percentage. The recordkeeping: a photo and floor plan of the office with its square footage and the home's total; the exclusive-use basis (the room's sole use documented); the administrative-activities basis (where the practice's administration is done, and the absence of another fixed location); the home's cost records (mortgage statements, tax bills, insurance, utilities) for the regular method; the depreciation schedule for the home's business share; the accountable plan document and reimbursement records for an S corporation; and the mileage log that the office unlocks. The failure modes: the non-exclusive room (the deduction fails and the mileage with it); the coworking membership that becomes the competing fixed location without anyone noticing; the S corporation consultant who dropped the deduction instead of reimbursing it; the regular method chosen for a home sold two years later (recapture on a small deduction); and the office claimed with no mileage log (the gateway opened and never walked through).

Key takeaways

• The test: exclusive use of a defined space, and principal place of business under the administrative-or-management rule — the practice's administration done at home with no other fixed location for it; the client's site doesn't count as yours, but a coworking desk might.
• Simplified vs regular: simplified (prescribed rate up to 300 square feet, no recapture) for small offices and homes likely to sell; regular (business-use share of actual costs plus depreciation) for long-held homes where the deduction is materially larger — the depreciation is recaptured at sale even within the section 121 exclusion.
• The mileage is the value: from a qualifying home office, every trip to a client is business travel — for a consultant driving to clients, worth many times the office deduction.
• S corporation consultants reimburse under an accountable plan (home use and mileage) — the deduction survives the election; dropping it forfeits real money.
• Renters apply the percentage to rent and utilities; extended engagements over a year in one location can shift the tax home.
• Records: photo, floor plan, square footage, the exclusive-use and administrative-activities basis, the cost records, the depreciation schedule, the accountable plan, and the mileage log.

Qualifying the consultant's home office

Designate the exclusive space (photo, floor plan, square footage). Document the administrative-activities basis (what's done there; no other fixed location — or the coworking desk's use limited to client meetings). Choose the method with the home's sale horizon in view. Start the mileage log from the day the office qualifies. S corporation: adopt the accountable plan; reimburse monthly. Extended engagements: watch the one-year rule. An afternoon that reclassifies the drive to every client.

Worked example

A supply-chain consultant works at two clients' sites three days a week, runs the practice from a converted bedroom (160 square feet of a 2,400-square-foot home, exclusive), and drives 11,500 miles a year to the clients. Principal place of business: the practice's billing, proposals, research, and bookkeeping happen in the home office; the clients' sites are theirs, not hers; no coworking membership — qualified. Method: she plans to keep the home for a decade — the regular method (6.7% of mortgage interest, taxes, insurance, and utilities plus depreciation on 6.7% of the home's basis) exceeds the simplified figure by a wide margin; the recapture at an eventual sale is noted in the file as the cost of the larger deduction. Mileage: all 11,500 miles are business travel from the home office — at the standard rate, a deduction roughly eight times the office deduction itself; the log runs on an app. Her S corporation (elected two years ago): the home office and the mileage are reimbursed under an accountable plan — monthly, documented — deductible to the corporation and tax-free to her; her prior preparer had told her the S election "ended the home office deduction," and two years of unreimbursed home use and mileage were recovered through the accountable plan going forward (the past years' reimbursements can't be made retroactively — the lesson cost two years). Her colleague's extended engagement — fourteen months at one client's city with lodging deducted throughout — tripped the one-year rule at month twelve; the last two months' lodging and per diem were personal, and the tax home question the calendar should have flagged arrived as an examination adjustment.

Official sources

The IRS states that "you must regularly use part of your home exclusively for conducting business," and offers a "standard deduction of $5 per square foot of home used for business (maximum 300 square feet)" as the simplified option, or the regular method allocating actual expenses by business-use percentage. — Internal Revenue Service, Home office deduction, https://www.irs.gov/businesses/small-businesses-self-employed/home-office-deduction

The IRS states that "if you use your car for business, charity, medical or moving purposes, you may be able to take a deduction based on the mileage." The business standard mileage rate is 76 cents per mile for July 1 through December 31, 2026 (72.5 cents for the first half of 2026); a taxpayer may instead deduct actual vehicle expenses. — Internal Revenue Service, Standard mileage rates, https://www.irs.gov/tax-professionals/standard-mileage-rates

Practitioner note

The consultant's home office is a gateway more than a deduction: the principal-place-of-business rule, met by doing the practice's administration at home with no other fixed location, turns the drive to every client into business mileage worth many times the office itself. Our consulting files document the exclusive room and the administrative basis, choose the method against the home's sale horizon because the depreciation is recaptured, and — for S corporation consultants — adopt the accountable plan that preserves the deduction the election supposedly ended, because the preparer who said Form 8829 no longer applies was right about the form and wrong about the deduction.

See also: For related guidance, see the consulting deductions guide; and browse every small business tax guide, by situation.

Next step

Fairlight Accounting is a cross-border accounting and tax practice with a U.S. Tax Desk and a Canadian Tax Desk. Our U.S. Tax Desk handles consultant home office and vehicle setup — the exclusive-use and administrative-activities documentation, method selection with recapture in view, accountable-plan reimbursement for S corporation owners, client-site mileage logging, and extended-engagement tax home review. See pricing or book a call.