How is a TDY handled in flight crew tax preparation?
TDY is the acronym for a temporary duty assignment used in the airline industry. It is not necessarily the same as a temporary assignment as defined by the IRS. It is important for crewmembers to distinguish between the two. A TDY as used in the airline industry has no standardized rules about time or duration, while the IRS definition of a temporary assignment does have specific duration requirements. If a crewmember on TDY wants to write-off travel expenses associated with getting to their temporary base, they must ensure that the TDY assignment also meets the time requirements of a temporary assignment as defined in IRS Publication 463.
To understand this, it is important to understand the concept of a tax home. Generally a pilot or flight attendant's tax home is their domicile, but in the case of a temporary assignment, that might or might not be true.