If the concern is that the TIAA Transfer Payout Annuity was set up to directly roll each annual distribution from the 401(a) plan to an IRA, you have a problem to resolve with TIAA since it is not permissible to roll to the IRA any portion of the distribution from the 401(a) plan that constitutes your RMD. As I mentioned, if your RMD does get rolled to a traditional IRA, it is considered to be an excess regular contribution to your traditional IRA that must be dealt with accordingly with a "return of contribution" from the IRA, not a regular distribution from the IRA.
This situation shouldn't be all that unusual for TIAA. They should be aware that the Internal Revenue Code prohibits them from directly rolling over any distribution from your 401(a) plan before a distribution of your RMD for this 401(a) plan is paid to you. One thing to double-check is that the Transfer Payout Annuity is actually held by your 401(a) plan and was not, in fact, rolled over to an IRA when the annuity was established. Had your entire 401(a) been rolled to an IRA, you would have received a From 1099-R for the rollover of your entire 401(a) balance. There's also may be the possibility of rolling the entire annuity in-kind to an IRA. If that can be done, the annual payout could then be moved to another IRA by nonreportable trustee-to-trustee transfer rather than by distribution and direct rollover, allowing the RMD to be taken from the destination IRA.
A final alternative might be to change the payout method to be a payment paid to you which you then roll indirectly, minus the amount of your RMD, to the IRA. The unfortunate consequence of this method is that 20% federal tax withholding is required on the portion that is eligible for rollover (the portion in excess of your RMD), and in some states, mandatory state tax withholding as well.
