IRS has released guidance on the conversion of 401(k) and 403(b) plan assets to Roth 401(k) or Roth 403(b) accounts in Notice 2010-84. This guidance also applies to governmental 457(b) plans beginning January 1, 2011. Here are the highlights: Plan participants, spouses, and alternate payees who are current or former spouses can do the in-plan Roth conversion.