The distribution from your TSP will be considered an "early withdrawal" since your are under 59.5. It will be added to your taxable income, and, you will be subject to a 10% penalty tax.
There are some exceptions to the penalty tax: Exceptions
to Withdrawal Penalty, which TurboTax can handle.
You should contact TSP to get form 1099-R, which will give you the exact numbers and codes to enter into TurboTax.
