how to deal with tenant leaving before contract expiration due to military/federal transfer? are there exceptions to consider?

The Servicemembers Civil Relief Act offers protections to service members and their dependents (Section 535 of the Act covers lease termination protections). I recommend that you review the provisions of the act to make sure you are in compliance with its requirements.  

Deposit refund. That depends on local or state law.

If you have a military person needing to get out of the lease early I would without a doubt let them do it without any penalties.

Peter Vekselman

Hope that helps, if I can be of any other assistance please do not hesitate to PM me directly.

You can ask for verification of duty change,, and then it's rent refund and sec dep refund if no damages.. 

Special rules for service personnel.  A large percentage of regular tenants do not respect a lease and will move when ever it suites their needs. Only difference is with regular tenants you can usually charge a lease breaking fee. If in this case you are allowed to charge a fee (not saying you are) there is no reason you would not. Tenants are tenants regardless of their career choice.  

May want to consider different tenant base in the future if this causes you a financial loss.

If they gave notice after the first of October they are responsible for the rent for November at a minimum depending on how long their notice is for..

Let them leave. If they have orders, they have legal exemption.

and even if they were lying about orders, they could hand you fake orders and you wouldn't know the difference (ask me how I know! LOL) Happens all the time, especially with younger troops.

"and even if they were lying about orders"

Is it not customary to confirm with commanding officers that they are actually being transferred. Why would a landlord take a tenants word at face value when they are breaking a lease ?????

@Carlos Chavez

Check out these links to help  you out.  They have to provide you with orders and if they can't then they are breaking the lease and should be charged a fee for this.  The first link is right from the govt.  This website states the person must provide a copy of the order to break the lease with no fee or penalty.  Deposit returned minus and standard damages.   I have added a clause to my lease to cover this.

http://www.militaryonesource.mil/web/mos/-/military-clause-terminate-your-lease-due-to-deployment-or-pcs?inheritRedirect=true&redirect=%2Fweb%2Fmos%2Fdeployment

http://rentlaw.com/military-clause/