To quote the PA Dept. of Revenue:
"IRAs are not subject to Inheritance Tax when the decedent is under the age of 59 1/2 at the time of death. For 401K’ s, the same provision applies unless the owner of the plan could have closed out the plan during their lifetime. In most plans, that right does not accrue until the "normal retirement age" is reached, which is usually 62 or 65 years of age."