If you are enrolling in the TDA Program for the first time, you may elect how to invest your future TDA contributions by logging in to the secure section of our website or by filing a paper TDA Enrollment Form (code TD1). If you are already a TDA participant, you may elect how to invest your future TDA contributions and any past TDA accumulations by logging in to the secure section of our website or by filing a paper TDA Investment Election Change Form (code TD45) on a quarterly basis. Investing in 5% multiples, you may choose any combination of TRS' Passport Funds.