In Rev. Rul. 2014-9, the IRS issued guidance on “roll-ins” to tax-qualified plans from other plans and IRAs.  Taking “bad” money can disqualify a plan.  Basically, if the plan of the former employer stated on its most recent Form 5500 that it is intended to be tax-qualified, then money can be taken from the former employer’s plan.  IRA money generally is alright as long as certain simple representations are made.