TDY
TDY: How Temporary Duty Travel Is Paid
TDY is duty performed away from your permanent duty station without your assignment changing. You travel, do something, and return; your unit and your station stay the same.
Example. A sergeant attends a four-week course at another post, or a maintenance team deploys for two weeks to support an exercise. Both are TDY. A reassignment to that post would be a PCS.
What it pays
Per diem covering lodging and meals at a rate set for the location, transportation to and from, and reimbursable expenses: baggage, tolls, official telephone use, rental vehicle where authorised.
The Air Force and Navy sometimes use TAD (temporary additional duty) for the same idea. Different label, same concept.
Where people lose money
Almost always in the paperwork rather than in the rules.
Reimbursement comes after. Much of a TDY is paid by the member and repaid on a claim. A junior member sent on short notice can be several thousand dollars out of pocket for weeks, and a government travel card exists precisely to prevent that, but only if it has been issued and activated before the trip.
Receipts govern. Expenses without documentation are not reimbursed, and the threshold above which a receipt is required is lower than most people assume.
The claim has a deadline. Filed late, it becomes an administrative problem; filed wrongly, it produces a debt that appears on a later pay statement without warning.
Lodging above the rate needs authorisation in advance. Booking a hotel over the per-diem ceiling and seeking approval afterwards is the classic and expensive mistake.
Why the distinction from PCS matters
Three reasons, and each has bitten someone. The entitlements differ. The tax treatment differs beyond a certain duration. And a family cannot accompany a member on TDY at government expense the way they can on a PCS — so an assignment structured as a long TDY as opposed to a PCS separates a family without the entitlements that go with a move.
How the money works
TDY travel is reimbursed rather than paid as an allowance. The two components are lodging, which is reimbursed against receipts up to a ceiling set for the location, and a daily amount for meals and incidental expenses, which is paid at a flat rate for that location as opposed to against receipts. Both are set by locality, which is why the same number of days costs the government very different amounts depending on where the duty is.
The mechanism is a travel voucher filed after the trip. Members are normally issued a government travel charge card for the expenses, and the settlement of the voucher is what clears it. The practical failure mode is the same everywhere: a voucher filed late leaves the member carrying the card balance, and a voucher filed without the lodging receipt does not clear at all.
Where it differs from a PCS
The two are frequently confused because both involve travel on orders, and almost nothing else about them is the same. A PCS moves the duty station and the household. TDY leaves both in place. A PCS carries an entitlement to ship household goods, a dislocation allowance and travel for dependents. TDY carries none of those, because there is nothing being relocated.
The consequence for a family is that a long TDY can be harder to absorb than a short PCS: the member is away, the household is running two locations in practice, and none of the relocation entitlements apply.
The variants worth knowing
Extended TDY, where duty at one location runs long enough that the flat daily rate is reduced on the reasoning that the member has settled into cheaper arrangements. TDY en route, where a course is attended between two permanent assignments and the travel is folded into the PCS. And the phrase “TDY and return”, which specifies that the member comes back to the same station afterwards rather than continuing on to a new one.
Questions and answers
How long can a TDY last?
Days to several months. Beyond a threshold the tax and entitlement treatment changes, which is why long assignments are sometimes structured as a PCS instead. The distinction is administrative, not about how long you are actually away.
Who pays for a TDY?
The government, through travel entitlements: per diem for lodging and meals, transportation, and reimbursable expenses. Most of it is reimbursement against a claim, which means the member frequently pays first and is repaid after, and that timing catches junior members out.