Trying to understand the tax implications involved. Is it only a one-time tax payment on the 401k money being converted into the Roth IRA? If so, I am ready to accept that hit... However, the representative from Fidelity began tossing around terms like "commingling" and "bookkeeping nightmare for years to come". She was, admittedly, not an expert on the subject and just trying to make sure I was aware of potential consequences. Most of the info I've been able to find on the subject seems a little outdated. Any clarification would be greatly appreciated...

Thanks!!