Let's be honest, per diem rules are confusing enough. You've got the daily rates, the high-cost cities, the lodging vs. meals breakdown. But nothing seems to trip up travelers and accountants alike quite like figuring out the per diem for the first and last day of travel. It feels like a trick question. Do I get the full amount? Half? Something in between?

I've been on both sides of this—the employee submitting an expense report with a sheepish note, and the manager trying to decipher policy to approve it. The confusion is real, and it often leads to under-claiming money you're owed or, worse, an awkward conversation during an audit.

So, let's cut through the jargon. This isn't about memorizing a government PDF (though we'll look at those). It's about getting your money right, hassle-free. We're going to break down the infamous "75% rule," see how different organizations handle it, and walk through real examples so you never have to guess again about your per diem first and last day of travel entitlements.

What Exactly is the "First and Last Day" Per Diem Rule?

At its core, the rule is about proportionality. A per diem is a daily allowance for meals and incidental expenses (M&IE). On a standard full travel day, you're away from home for 24 hours, presumably needing breakfast, lunch, dinner, and those little costs like tips and snacks. But on the day you leave and the day you return, are you really incurring costs for three full meals?

Probably not. If you catch a 3 PM flight, you likely ate lunch at home. Your travel day expenses might only start with an airport dinner. That's where the standard rule comes in.

This directly addresses the core search for "per diem first and last day of travel." It's the 75% rule. But here's where people stop reading and get into trouble. They apply it blindly.

How to Calculate It: Step-by-Step (Without the Headache)

Let's move from theory to your expense report. Here’s how you actually figure out what to claim.

Step 1: Find Your Full M&IE Rate

First, know the full per diem rate for your destination. For most in the US, this means the GSA per diem rates. Let's say you're traveling to Chicago, IL. For 2024, the standard M&IE rate for Chicago is $79.

Step 2: Apply the 75% Multiplier

Calculate 75% of that M&IE rate. For Chicago: $79 x 0.75 = $59.25. That's your M&IE allowance for both your departure day to Chicago and your return day home.

Step 3: Handle Lodging Separately

Lodging is paid at the full allowable rate for the location for any night you need a hotel. If you need a hotel on your first night in Chicago, you claim the full Chicago lodging rate (let's say $258). The 75% rule doesn't touch this.

Simple, right? But the devil is in the exceptions.

The Big Exceptions and "It Depends" Scenarios

If life were simple, we'd all follow the GSA rule and be done. But travel isn't simple. Your company or specific circumstances might change the game.

Exception 2: Your Company's Internal Policy is King

This is the most important point. The GSA rules are a guideline for federal employees. Private companies can adopt, modify, or ignore them. I've seen policies that are all over the map:

• The Stickler: "We follow GSA 75% to the letter." Common in large, traditional corporations.
• The Simplifier: "We just give you the full M&IE rate every calendar day you're traveling." This is surprisingly common in tech and startups. It's less admin work and seen as a perk.
• The Hybrid: "75% rule, but only if your travel spans less than 8 hours on that day." Some companies try to be "fairer" with time thresholds.

You must find your company's travel and expense policy. It's the final word. Don't assume. An incorrect claim based on a blog post (even this one!) won't fly with your finance team.

Exception 3: International Travel Gets Weird

The U.S. Department of State sets per diem rates for foreign locations. Their rules for the first and last day can differ. Often, they also use a percentage (like 75%) but sometimes it's tied to the specific arrival/departure times in the new time zone. Always check the specific calculation notes for your destination country on the State Department site.

A Real-World Example: Sarah's Business Trip

Let's make this concrete. Sarah works for a company that follows standard GSA-type rules.

• Trip: Home (Dallas) to Boston, MA for a conference.
• Dates: Depart Monday 2 PM, return Thursday 6 PM.
• Rates (2024 Example): Boston M&IE = $79, Boston Lodging = $298.

Here’s how her per diem first and last day of travel breaks down:

See the pattern? The M&IE on the bookends is lower. The lodging is untouched for nights she actually needed it. If her company gave the full M&IE every day, she'd get $79 on Monday and Thursday—an extra $39.50. Not a fortune, but it adds up across a company.

Common Questions (And The Real Answers)

Here are the specific questions people are actually googling, answered plainly.

What if my travel starts or ends at midnight?

The rule is based on calendar days, not a 24-hour clock. If you start driving at 11:30 PM on Tuesday, Tuesday is your first day of travel (even if only 30 minutes fall on it). You'd claim 75% of that day's M&IE. It feels odd, but it's about administrative simplicity.

Does the 75% apply if I'm driving, not flying?

Yes. The mode of transport doesn't matter. It's about being in a travel status away from your home or office location.

What about partial days in the middle of a trip?

Ah, a great question that most guides skip! The 75% rule is specifically for the first and last calendar day of the trip. If you have a partial day in the middle (e.g., you fly from Boston to a client in Providence, RI, for a half-day meeting), the standard rule doesn't directly address it. Most companies would either:
1) Give you the full M&IE rate for the primary location that day, or
2) Have a separate rule for intra-trip travel (often prorating between the two cities' rates).
Check your policy. This is a genuine gray area.

I'm traveling for over 30 days. Does the rule change?

For long-term travel, the per diem rules often change (rates typically drop after 30 days). However, the first and last day rule still applies to the first calendar day you leave and the last calendar day you return, regardless of the trip's total length.

Practical Advice: How to Never Get This Wrong Again

After all this, how do you make it bulletproof for yourself? Here's my actionable list.

1. Locate and Read Your T&E Policy. Seriously. Search the intranet for "travel and expense policy." Ctrl+F for "first and last day" or "75%." Know your battlefield.
2. Bookmark the Key Sites. Have the GSA Per Diem page and, if applicable, the Defense Travel Management Office site ready.
3. Use a Calculator or Template. Create a simple spreadsheet template. Input your dates, locations, and full M&IE rates. Have a formula that automatically applies 75% to the first and last date cells. It takes 10 minutes to set up and saves hours of doubt.
4. Ask Before You Travel. If your policy is unclear, a quick email to finance or your manager saves a reconciliation headache later. Phrase it like: "Just confirming, for my upcoming trip, do we apply the GSA-style 75% M&IE rule on the first/last day?"
5. Document Your Logic. On your expense report, in the notes field for the first and last day line items, just add "(75% per policy)." It shows you didn't just guess and makes the approver's life easier.

The Bottom Line: It's About Fairness, Not Nickels and Dimes

At the end of the day, the per diem first and last day of travel rule exists to be fair—to both the traveler and the employer. It recognizes that your expense pattern is different on those days. Whether it's the GSA's 75%, the DoD's time-based proration, or your startup's full-day allowance, the principle is the same: align the allowance with the likely expense.

My personal take? The GSA's 75% rule is a good compromise. The DoD's method is more accurate but overly complex for most. And the "full day every day" policy, while generous, can feel a bit like overpaying for a departing employee who eats a big breakfast at home. But hey, if that's the policy, claim it with a clear conscience!

The goal is to move from confusion to confidence. You shouldn't be stressing about meal allowances when you should be focusing on your presentation or client meeting. Now you have the map. You know where the rule comes from (GSA), how to calculate it (M&IE x 0.75), and the major exceptions (DoD, company policy, international).

So next time you book a trip, the question of per diem first and last day of travel won't be a question at all. It'll just be a quick calculation, a note on your report, and one less thing to worry about. And that's the whole point.