Anti-Cutback: Timing Amendment Affect Benefits in Pay Status?

[rocknrolls2]

401(k) Plan A is merged into 401(k) Plan B. 401(k) Plan A permits recalculation of minimum distributions to be made monthly and provides for monthly installment. 401(k) Plan B permits only annual recalculation and provides for annual installments.

Minimum Distribution Recalculation. Under Code Section 401(a)(9)(D), recalculation is permitted no more frequently than annually. Thus, it appears that monthly recalculation is illegal and annual recalculation can be permitted going forward.

Anti-Cutback Rule. The tricky issue is this: the current final anticutback regs permit an amendment to an optional form of distribution affecting timing only to no more than two months of the timing of a pre-amendment distribution form (6 months for in-service distributions). Thus, it appears that 401(k) Plan B would be permitted to change the availability of minimum distributions to former 401(k) Plan A participants to quarterly installments. My question is, can this amendment also apply to participants currently receiving minimum distributions?