Per Diem on TDY — The Math People Get Wrong
The Joint Travel Regulations is 1,400+ pages. Chapter 2 is the part that pays your TDY. Here's what actually matters for your voucher — the lodging ceilings, the M&IE math, the travel-day cut, the meal deductions that catch people off-guard, and the audit traps that get reimbursements clawed back six months after you got home.
TDY per diem is two separate buckets: lodging at actual cost up to a locality ceiling, and a flat Meals & Incidental Expenses (M&IE) daily rate. They are governed by different rules, deducted in different ways, and audited differently. Confusing the two is the #1 reason TDY vouchers come back red. Source: JTR Chapter 2 (Jan 2026), DTMO per diem program.
Two Locality Systems: GSA vs DoD
Per diem rates depend on whether your TDY is inside the continental United States or outside. The rate publishers are different.
- • CONUS (48 contiguous states + DC): Rates set by the General Services Administration (GSA) annually for the federal fiscal year (Oct 1 – Sep 30). Published at gsa.gov/perdiem. The military uses the GSA rate without modification.
- • OCONUS (Alaska, Hawaii, US territories, foreign): Rates set by the DoD Defense Travel Management Office (DTMO) for non-foreign OCONUS, and by the State Department for foreign locations. Published at travel.dod.mil/Allowances/Per-Diem.
A locality outside the named non-standard areas gets the "Standard CONUS" rate — currently $68 M&IE plus a $110 lodging ceiling in FY26. Higher-cost cities are tiered separately. DTS pulls the rate for your TDY location automatically; verify it matches your orders.
M&IE Is Three Meals Plus a $5 Incidental
M&IE is not one number — it is a stack of four. JTR Appendix A breaks each daily rate into a breakfast portion, lunch portion, dinner portion, and a flat $5 incidental. This matters because when a meal is provided to you (conference, hotel breakfast included, DFAC access on base), only that meal's portion is deducted — not the whole day.
| Tier | Bkfst | Lunch | Dinner | Incid. | Total |
|---|---|---|---|---|---|
| Standard CONUS | $18 | $20 | $31 | $5 | $68 |
| CONUS Tier 1 | $18 | $20 | $34 | $5 | $77 |
| CONUS Tier 2 | $19 | $22 | $40 | $5 | $86 |
| CONUS Tier 3 | $23 | $26 | $41 | $5 | $95 |
Source: JTR Appendix A, Meals & Incidental Expenses (FY26). CONUS tiers shown are examples — verify your specific locality at gsa.gov/perdiem. OCONUS rates are per-locality and not tier-banded the same way.
The 75% Travel-Day Rule
The day you depart your PDS and the day you return are travel days. JTR pays M&IE on travel days at 75% of the locality rate, regardless of what time you leave or arrive. Both bookends of the trip get the cut.
Standard CONUS example: $68 M&IE × 75% = $51 for your departure day and $51 for your return day. Days fully on-site at the TDY location get the full $68. Lodging on travel-day nights is reimbursed at actual cost up to the local lodging ceiling — the 75% cut does NOT apply to lodging.
For OCONUS travel that crosses the international date line, the "travel day" concept still applies at the locality M&IE rate of wherever you slept that night. DTS handles this calculation if you enter your itinerary accurately.
Proportional Meal Deductions
If a meal is provided at no cost to you — government cafeteria, conference catering, hotel breakfast included in the room rate, in-flight meal on military air — the corresponding meal portion is deducted from your M&IE for that day. You keep the rest. The $5 incidental is never deducted; you get it even on days when all three meals are provided.
Two specific gotchas that catch people:
- • Hotel continental breakfast. If it's included in the room rate (not optional, not paid separately), the breakfast portion gets deducted. If the hotel charges separately and you pay your own way, no deduction.
- • Conference-provided meals. Look at your orders or the conference agenda. If a working lunch is on the schedule and it's "included," that lunch portion is deducted. Document it the day-of so your voucher reflects reality — finance will check the agenda when they audit.
Source: JTR Appendix A & JTR 020302; DoDI 5154.31 Vol 5 on travel allowances.
Lodging Is Actual Cost — Up to a Ceiling
Lodging works opposite to M&IE. You submit the receipt for what you actually paid, and finance reimburses that amount up to the locality lodging ceiling. Anything above the ceiling is out-of-pocket unless your Authorizing Official approved Actual Expense Allowance (AEA) in writing before you booked.
Three rules to internalize:
- • Taxes are reimbursable separately in CONUS — most localities tax-exempt federal lodging. If the hotel charges tax, request a tax-exempt form. Lodging tax (when charged) is reimbursed outside the ceiling.
- • Resort fees, parking fees, and Wi-Fi are usually NOT reimbursable unless authorized as a separate expense on your orders. Try to book hotels that include them.
- • Government quarters (on-base lodging) come first. If government quarters are available and you stay off-base anyway, you may be reimbursed at the government-quarters rate only — not the full commercial rate. Get a Certificate of Non-Availability (CNA) from on-base lodging before booking a hotel.
The 30/180-Day Compression (Long-Term TDY)
If your TDY at one location runs more than 30 consecutive days, the rate compresses. The assumption is that you'll switch from a hotel to an extended-stay or apartment and start cooking some meals.
| Duration | Per Diem Rate | What it means |
|---|---|---|
| Days 1–30 | 100% of locality per diem | Full lodging ceiling + full M&IE. |
| Days 31–180 | 75% of locality per diem | Both lodging ceiling AND M&IE are reduced to 75%. |
| Days 181+ | 55% of locality per diem | Long-duration TDY rate. Lodging ceiling AND M&IE at 55%. |
Source: JTR 020303, Long-Term TDY. The 75% rate applies to both lodging ceiling AND M&IE, not just one. The AO can authorize a higher "not to exceed" lodging rate in extenuating circumstances but it must be documented in writing on the orders.
The Government Travel Card and Split Disbursement
The Government Travel Charge Card (GTC) is mandatory for most TDYs over 24 hours under the GSA SmartPay program. It is an Individually Billed Account (IBA) — the card is in your name, your credit, your liability. You charge official travel expenses to it and finance reimburses you (or directly pays the vendor) on the back end.
Split disbursement is the routing logic DTS uses to send reimbursement money to two destinations from the same voucher:
- • Lodging and rental car charged to the GTC → reimbursement routes directly to Citibank to pay off those charges.
- • M&IE and any expenses paid out-of-pocket (personal card, cash) → reimbursement routes to your personal checking account.
The total you receive is identical; it just lands in two places. Split disbursement is mandatory for GTC-charged lodging and rental car under DTMO policy — it's the system that keeps your GTC from going delinquent while finance processes the voucher.
Allowable vs Unallowable Expenses
Outside M&IE and lodging, you can claim certain "miscellaneous reimbursable expenses" on your voucher. The list is finite and the audit is real.
- • Taxi / rideshare to/from airport and TDY location
- • Parking at airport (long-term) — receipts required over $75
- • Baggage fees (first checked bag, sometimes second on TDY orders)
- • Tolls and fuel for an authorized rental car
- • Authorized business phone calls (rare; mostly OCONUS)
- • Lodging tax in CONUS (separate from ceiling)
- • Currency conversion fees on official OCONUS purchases
- • Mini-bar, room service tips, alcohol
- • In-room movies, hotel gym fees, spa
- • Personal entertainment (golf, sightseeing, attractions)
- • Personal phone calls, personal Wi-Fi
- • Resort/destination fees (unless pre-approved)
- • Hotel parking (unless no alternative + pre-approved)
- • Pet boarding, dependent travel (unless on orders)
- • GTC late fees you incurred yourself
Source: JTR Chapter 2, Section 0205 (Miscellaneous Reimbursable Expenses). Receipts required for any single expense ≥ $75 except lodging and rental car (always required).
DTS Workflow — Authorization → Voucher → Audit
The Defense Travel System is the workflow. Every TDY has three documents that flow through it.
Source: DoDI 5154.31 Vol 5; DTMO DTS Manuals. Keep receipts for 6 years after travel — this is the audit retention window.
The Questions People Actually Ask
What exactly does TDY per diem cover?
Two buckets. Lodging is reimbursed up to the locality lodging ceiling at actual cost (receipt required). Meals & Incidental Expenses (M&IE) is a flat per-day rate that pays whether you eat ramen or steak. The M&IE rate bundles three meals plus a $5/day incidental component. You do not submit meal receipts for M&IE — it is a flat allowance.
Why did my first and last day get cut to 75%?
JTR Chapter 2 pays travel days at 75% of the locality M&IE rate. This applies to the day you depart your PDS and the day you return — both ends. It is not a punishment for arriving late or leaving early; it is the standard rule. If your standard CONUS M&IE is $68, your travel-day M&IE is $51. Lodging on those nights is still reimbursed at actual cost up to the ceiling.
My hotel gave me free breakfast. Do I lose the breakfast portion?
Yes — if the meal is provided by the government, the conference, or otherwise included at no cost to you, the corresponding meal percentage is deducted from your M&IE. Hotel-provided continental breakfast included in the room rate is a common deduction trigger. The proportional meal-rate table in JTR Appendix A spells out the breakfast/lunch/dinner percentages by locality M&IE tier. You should still receive the $5/day incidental even if all three meals are provided.
Why does my voucher say my hotel cost more than my reimbursement?
You exceeded the locality lodging ceiling. Per diem lodging is "actual cost not to exceed" the published ceiling — anything above the ceiling is out-of-pocket unless your AO pre-approved actual-expense lodging in writing (rare, requires justification). Always check the GSA or DTMO ceiling for your TDY location before booking and book at or below.
What is the $5/day incidental supposed to cover?
Per JTR Appendix A, the incidental portion of M&IE is set at $5/day inside CONUS. It is meant to cover fees and tips to porters, baggage carriers, hotel staff, transportation between lodging and meal locations, and similar small expenses. You receive the full $5 even when meals are provided. OCONUS incidental rates differ and are set by DoD per locality.
Can I use my GTC for personal stuff during the TDY?
No. The Government Travel Charge Card is for official travel expenses only — lodging, rental car, meals, taxi/rideshare to/from official sites, and authorized incidentals. Personal purchases on the GTC violate DoD card-program policy and are typically caught in the post-travel audit. The card is in your name (IBA) — you are personally liable for the bill, even though you are reimbursed for official charges.
Why did finance only reimburse part of my voucher to me and the rest to Citibank?
That is split disbursement working correctly. DTS routes lodging and rental car charges directly to the GTC vendor (Citibank) and M&IE plus other personal-card or cash expenses to your personal account. The total reimbursement is the same — it just lands in two places. Split disbursement is mandatory in most cases for any expense charged to the GTC.
My TDY got extended. Do I get more per diem or does it switch to long-term rates?
TDY at one location for more than 30 consecutive days triggers the "flat rate" per diem reduction under JTR 020303 — 75% of the locality per diem for days 31–180, and 55% for days 181+. The intent is that long stays mean you cook your own meals and rent something cheaper than a hotel. Both ceilings still apply per day; the rate is just compressed.
- • GSA Per Diem Rates (FY26 CONUS) — gsa.gov/travel/plan-a-trip/per-diem-rates
- • DTMO Per Diem (OCONUS + DoD program) — travel.dod.mil / Allowances / Per-Diem
- • Joint Travel Regulations (JTR), Chapter 2 & Appendix A — travel.dod.mil / JTR.PDF
- • DoD Financial Management Regulation 7000.14-R, Volume 9 (Travel Policy) — comptroller.defense.gov/fmr
- • DTS & GSA SmartPay 3 — Defense Travel Management Office — travel.dod.mil