I have no idea about other 401k plans, but the distribution protocol for the TSP is actually in the Code of Federal Regulations. https://www.ecfr.gov/current/title-5/chapter-VI/part-1650 5 CFR 1650.2(h) A participant may elect to have his or her TSP withdrawal distributed from the participant's traditional balance only, Roth balance only, or pro rata from the participant's traditional and Roth balances. Any distribution from the traditional balance will be prorated between the tax-deferred balance and any tax-exempt balance. Any distribution from the Roth balance will be prorated between contributions in the Roth balance and earnings in the Roth balance. In addition, all TSP withdrawals will be distributed pro rata from all TSP core funds in which the participant's account is invested. All prorated amounts will be based on the balances in each TSP core fund or source of contributions on the day the TSP withdrawal is processed. |