Business Travel Deduction Rules: The Overnight Test, Per Diems, and What You Can Write Off

By Yarik Yarosh, CPA ·September 5, 2026 ·6 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

Business travel expenses are deductible under IRC 162 as ordinary and necessary business expenses, but only when the travel requires the taxpayer to be away from their tax home “substantially longer than an ordinary day’s work” and requires sleep or rest (the “overnight test” from United States v. Correll, 389 U.S. 299 (1967)). The tax home is generally the taxpayer’s regular place of business, not their personal residence. A taxpayer who drives two hours to a client, works a full day, and drives home the same night cannot deduct travel expenses (this is a local business trip). A taxpayer who flies to a client, stays overnight in a hotel, and flies back the next day can deduct airfare, hotel, meals (50%), ground transportation, and incidental expenses. Temporary assignments (expected to last less than one year) qualify; indefinite assignments (expected to last more than one year) do not.

✓Key takeaway

What’s deductible on a business trip (overnight stay):

Expense	Deductible?	Limitation
Airfare / train / bus	100%	Must be primarily for business
Rental car	100% (business use)	Personal side trips pro-rated out
Lodging (hotel)	100%	Reasonable, not lavish
Meals	50%	Business purpose required
Taxi / rideshare / parking	100%	Business-related only
Baggage fees	100%
Dry cleaning on trip	100%
Tips (taxi, bellhop, porter)	100%
Internet / phone on trip	100%	Business-related
Conference registration fees	100%

What’s NOT deductible:

Expense	Why Not
Commuting (home to regular office)	Personal expense, never deductible
Travel for a trip primarily personal	Must be “primarily for business”
Spouse’s travel expenses	Unless spouse is an employee with a business purpose
Personal sightseeing during a business trip	Only business days/activities deductible
Lavish or extravagant expenses	IRC 162(a)(2)

The “primarily for business” test (domestic travel):

Days on Trip	Business Days	Personal Days	Deductibility
5 days	4 business, 1 personal	Weekend sightseeing	Transportation: 100% (primarily business). Lodging/meals: only business days
5 days	2 business, 3 personal	Extended vacation	Transportation: NOT deductible (primarily personal). Lodging/meals: only business days

The international travel rule (different from domestic): For trips outside the US lasting more than 7 days where personal activities exceed 25% of the trip:

Trip	Allocation
10 days international, 7 business + 3 personal	Airfare: allocated 70% deductible (7/10). Lodging/meals: business days only

Domestic trips do not require airfare allocation. If the trip is primarily business, the entire round-trip airfare is deductible.

Per diem rates (simplified substantiation):

Location	2025 GSA Lodging Rate (varies)	M&IE Rate
Standard (most US cities)	$107/night	$68/day
High-cost cities (NYC, SF, DC)	$200-$400+/night	$79/day

Using per diem for meals: instead of keeping every individual meal receipt, the taxpayer can use the GSA M&IE rate as the deduction. The standard $68/day M&IE rate ($79 high-cost) applies automatically. Only 50% of the meal component is deductible. The lodging per diem is available only to employers reimbursing employees; self-employed individuals must use actual lodging costs with receipts.

How does a business owner maximize travel deductions?

Hypothetical example

Round numbers. A consultant. S-Corp. Travels from Tampa to New York City for a 3-day client engagement. Adds 1 day of personal sightseeing.

Trip structure:

Day	Activity	Business or Personal
Monday	Fly Tampa to NYC, client meeting afternoon	Business
Tuesday	Full-day client workshop	Business
Wednesday	Client follow-up morning, fly home evening	Business
Thursday	Sightseeing in NYC, fly home evening	Personal

Actual expenses:

Expense	Amount	Deductible
Round-trip airfare	$350	$350 (100%, trip is primarily business: 3 of 4 days)
Hotel, 3 nights (Mon, Tue, Wed)	$750 ($250/night)	$750 (100%, all business nights)
Hotel, 1 night (Thu, personal)	$250	$0
Meals, 3 business days	$180	$90 (50% of $180)
Meals, 1 personal day	$60	$0
Taxi/rideshare (business-related)	$120	$120
Taxi (personal sightseeing)	$40	$0
Checked bag	$35	$35
Total trip cost	$1,785
Total deduction		$1,345

Per diem alternative (meals only): Instead of tracking individual meal receipts, the consultant uses the NYC per diem M&IE rate: $79/day.

Item	Amount
Per diem meals, 3 business days	$79 x 3 = $237
50% limitation	$237 x 50% = $118.50

Per diem gives a $118.50 deduction vs. $90 using actual receipts. The per diem is higher because NYC’s M&IE rate ($79) exceeds the actual spending ($60/day). Using per diem saves $28.50 AND eliminates the need to keep meal receipts.

The “travel day” rule: Days spent traveling to and from the business destination count as business days. If the consultant flies to NYC on Sunday evening (arriving late, no business activity), Sunday still counts as a business travel day.

Extending a trip for cheaper airfare: The consultant’s client meeting is Tuesday through Wednesday. A round-trip flight departing Monday and returning Wednesday costs $450. Staying through Saturday (personal days Thursday through Saturday) drops the airfare to $250, and adding 3 nights of hotel ($750) is still cheaper than the $200 airfare savings.

Tax result: The cheaper airfare ($250) is fully deductible. The extra hotel nights (Thursday through Saturday) are personal and not deductible. But the consultant saves $200 in airfare, and $250 is deducted instead of $450. Net effect: the consultant spends less AND deducts less. This can make sense when the airfare savings exceed the personal hotel cost, but each dollar of personal hotel is non-deductible.

Combining business and personal travel (domestic): The consultant adds 2 days of vacation to a 5-day business trip.

Scenario	Transportation	Lodging/Meals
5 business + 2 personal (trip is primarily business)	Airfare: 100% deductible	Business days only
2 business + 5 personal (trip is primarily personal)	Airfare: NOT deductible	Business days only

The break-even: if business days are 50% or more of the trip, the airfare is fully deductible for domestic travel. Below 50%, the entire airfare becomes personal.

Documentation required: For each business trip:

Business purpose of the trip
Dates of departure and return
Days spent on business activities
Receipts for lodging, transportation, and other expenses ($75+)
Meal log or per diem election
Name and business relationship of people met

Without this documentation, the entire deduction is at risk in an audit. The Cohan rule (estimates in lieu of records) does NOT apply to travel expenses per IRC 274(d).

Illustrative numbers only, not a real client and not advice for your facts.

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Cite this page

Yarik Yarosh, CPA. "Business Travel Deduction Rules: The Overnight Test, Per Diems, and What You Can Write Off." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-travel-deduction-rules-overnight-test

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.