I suggest you not do backdoor Roth if you can't separate pre-tax and after-tax contributions. Vanguard's 401k has a way to withdraw the after-tax contribution immediately to a separate Roth 401k - but you have to really be sure you can do that. Once mixed, it's a pain in the ass and not worth it imo (just keep your after-tax money and do some other investment).
https://www.huajielamatuan.com/post/202022200004
and if your current employer has a bad 401K, roll your tradtional IRA to a Solo 401K.
mark。。。。
你如果只是一个employee,自己名下没有公司,是设立不了solo 401k的。
但我不是self employed啊,没有business income, 怎么开solo 401k 呢?
How to backdoor roth pre-tax money?
如果backdoor的时候traditional IRA里有部分pre-tax部分after-tax的钱,要按照pro rata rule来对pre-tax的钱来收税。所以楼上的才建议把所有traditional IRA 里pre-tax的钱转到pre-tax 401k里去再backdoor。