Business trips rarely stay in one city. A Monday in San Francisco, Tuesday and Wednesday in Los Angeles, then home — how do you calculate per diem across three rate zones? The rule is simple: each travel day uses the rate for the city where the night is spent, and the first and last days of the whole trip get the 75% M&IE reduction.
The Basic Rule
- Lodging uses the cap of the city where you spend each night.
- M&IE uses the rate of the city where you are at the end of the day (overnight destination), with the first and last days of the entire trip at 75%.
- Day trips between cities follow the overnight location.
Worked Example: 5-Day West Coast Trip
| Day | Overnight | Lodging cap | M&IE | Daily total |
|---|---|---|---|---|
| Mon (first) | San Francisco | $259–$272 | $69 (75%) | ~$341 |
| Tue | Los Angeles | $191 | $86 | $277 |
| Wed | Los Angeles | $191 | $86 | $277 |
| Thu | San Francisco | $259–$272 | $86 | ~$358 |
| Fri (last) | — | — | $69 (75%) | $69 |
Note the last day: no lodging night, so only M&IE at 75% applies. The trip calculator does this automatically for a single city; for mixed cities, add one calculation per overnight city.
Multiple Cities in One Trip: Checklist
- List each overnight city and the nights stayed.
- Look up each city's monthly lodging cap on its city page.
- Apply the 75% M&IE rule only to the first and last days of the entire trip.
- Sum lodging nights + M&IE days for the total allowance.
IRS High-Low Simplifies This
Under the high-low method, a mixed trip collapses to two buckets: days in high-cost localities at $319 and days elsewhere at $225. No per-city lookup. That is a major reason national employers prefer it. See the high-low guide for the FY2026 list.
Use the Calculator Per City
Run the DayFig calculator once per overnight city with that city's date range, then add the results. First/last-day treatment: only the true first and last days of the trip get 75% — intermediate city-boundary days pay full M&IE.
Source: FTR §301-11.101 (M&IE), GSA FY2026 rates retrieved 2026-08-19.