Deemed IRAs are uncommon. A deemed IRA is essentially a separate IRA account managed by the 457(b) plan provider but otherwise treated independently of the 457(b). If all of you own contributions to the 457(b) were reported with either code G or code EE in box 12 of your Forms W-2, you do not have a deemed IRA and nothing about your 457(b) is an IRA. If you had a deemed IRA, you would not be asking this question because you would already have to have known that it was a deemed IRA to be able to make and properly report the contributions to the deemed IRA. If you had a deemed IRA, you would have received Forms 5498 reporting the contributions you made to the deemed IRA.
Since your participation in the 457(b) almost certainly does not involve a deemed IRA, any QCD would have to be made by first rolling funds from the traditional account in the 457(b) to a traditional IRA, then making the QCD from the traditional IRA. If you have reached the age where you are required to take an RMD from the 457(b), you must first satisfy that RMD before rolling over any other amounts to an IRA.
