How Does the 100-Mile Rule Work for the Reservist Travel Deduction?
“More than 100 miles from home” sounds simple until you ask what counts as home, and how to measure. This guide gives the IRS wording on both and is plain about what the IRS leaves unsaid.
What the rule says
Publication 463 says that if you are a member of a reserve component and you travel more than 100 miles away from home in connection with your performance of services as a member of the reserves, you can deduct your travel expenses as an adjustment to gross income rather than a miscellaneous itemized deduction. The same publication says you cannot deduct expenses of travel that does not take you more than 100 miles from home as an adjustment to gross income. The Schedule 1 instructions for line 12 use the same distance language.
The statute that creates the adjustment also says “more than 100 miles away from home,” and covers any period during which you are that far away in connection with the service.
On its plain wording, “more than 100 miles” means a trip of exactly 100 miles does not meet the distance test. Here is the test applied to some sample distances, calculated by a script. These are invented numbers and a test of the wording only; they are not about measurement:
| Distance | Distance test (more than 100) |
|---|---|
| 60 miles | Does not pass |
| 100 miles | Does not pass |
| 101 miles | Passes |
| 250 miles | Passes |
A worked example of the distance test
For example, take two reservists who both drill on the same weekend. The first lives 101 miles from the armory by the method they documented, and the second lives 100 miles away by the same kind of measurement. On the plain wording, the first passes the distance test because 101 is more than 100, and the second does not, because exactly 100 is not more than 100. The second reservist's drive is still real, and the miles are still driven, but the adjustment to gross income is not available for that trip. If the second reservist's measured distance were 101 miles using a different, equally reasonable method, the safe course is to write down which method was used, apply it to every drill, and ask a tax professional rather than pick whichever figure helps. The sample table above and this example use invented distances to test the wording only.
What “home” means
For travel, the IRS uses the term tax home. Publication 463 says that generally your tax home is your regular place of business or post of duty, regardless of where you maintain your family home, and that it includes the entire city or general area in which your business or work is located.
The IRS text we reviewed does not say that the “home” in the 100-mile condition is the same thing as the tax home described above. It defines tax home for business travel generally, and the reservist rule says “home” without defining it. So we cannot tell you from the IRS wording which place distance is counted from. If you maintain a family home in one place and work or drill somewhere else, confirm the starting point before you rely on it. How the IRS applies tax home to a reservist whose civilian job and reserve unit are in different places is not spelled out in the lines we reviewed either.
The IRS also defines traveling away from home. You are traveling away from home if your duties require you to be away from the general area of your tax home substantially longer than an ordinary day’s work and you need to sleep or rest to meet the demands of your work while away. You do not have to be away a whole day or from dusk to dawn, as long as your relief from duty is long enough to get necessary sleep or rest.
For reservists specifically, section 162(p) says you are deemed to be away from home in pursuit of a trade or business for any period during which you are away from home in connection with your service. That speaks to being away from home for business-travel purposes; the 100-mile condition is a separate requirement stated alongside it.
Edge cases the IRS text does address
- Permanent overseas duty. A member of the U.S. Armed Forces on a permanent duty assignment overseas is not traveling away from home.
- Commuting. The IRS says you cannot deduct commuting expenses no matter how far your home is from your regular place of work. A long drive to your regular workplace does not become deductible because it is long.
How distance is measured: the IRS does not say
This is the question readers ask most, and the honest answer is that the IRS publications we reviewed do not state a method. We read Publication 3, Publication 463 and the Form 2106 instructions for any wording about measuring the distance, such as one way versus round trip, driving route versus straight line, and found none. The only IRS wording is “more than 100 miles away from home.” Our reading: the law's wording is “more than 100 miles away from home”, which we read as the one-way distance from home to the duty location, not the round trip; what the IRS text does not say is how to measure that distance (road miles or a straight line).
You may see other sources state a specific method as if it were a rule. Treat any such method as an opinion unless you can point to IRS text. If your trip is close to 100 miles and the method would change the answer, that is the moment to ask a tax professional or the IRS, rather than pick the more favorable number.
Documenting the distance you used
Because no method is prescribed, we suggest writing down what you did. This is our suggestion, not an IRS requirement. Note the starting point you treated as home, the destination, the number of miles, and how you obtained that number (a mapping service, an odometer reading, or both), and keep a copy of the result. Then use the same approach every time so your records agree with each other.
The IRS requires proof of travel expenses. Publication 463 says you cannot deduct amounts that you approximate or estimate, that you should keep adequate records or sufficient evidence to support your own statement, and that a written record is generally needed. It suggests an account book, diary, log, statement of expense or trip sheet, plus documentary evidence such as receipts, canceled checks or bills. Documentary evidence is not needed for an expense, other than lodging, of less than $75. A hotel receipt is enough if it shows the name and location, the dates, and separate amounts for lodging, meals and telephone calls.
Those lines are about expenses generally. They do not say what evidence of distance the IRS expects, so documenting your mileage figure as above is our suggestion rather than a stated requirement.
Related questions
Which kinds of duty count is covered in which trips count. What you can claim for the trip itself is in the travel costs guide and the per diem guide.
Related guides
- Which trips count: sorting drill weekends, schools and annual training against the test.
- Mileage records: how to log the miles you drive on each trip.
- Travel costs: what goes on the form once a trip clears the distance test.
- Glossary: plain definitions of tax home and the other terms used here.
- FAQ: short answers to the questions readers send most.
- Form 2106 to Schedule 1: where the distance condition shows up on the forms.
Sources
- IRS Publication 463, Travel, Gift, and Car Expenses
- IRS Publication 3, Armed Forces' Tax Guide
- IRS Instructions for Form 2106, Employee Business Expenses
- IRS Instructions for Form 1040 and Schedule 1
- 26 U.S.C. 62, Adjusted gross income defined (U.S. Code, govinfo.gov)
- 26 U.S.C. 162, Trade or business expenses (U.S. Code, govinfo.gov)