Tbills

Terry Says

If you withdraw money from your 403(b) plan then you’ll have to pay ordinary income taxes on it. That could boost your tax bracket or make your Medicare Part B premium go up.

Just invest INSIDE your plan in the safest possible way at this stage — likely a money market fund for at least half your money.
If you are no longer working,and if your 403(b) doesn’t offer a safe investment, read this article and follow instructions to ROLL your account to Fidelity or Vanguard in an IRA Rollover,where you CAN invest inside the IRA in money market funds.