There is a lot of information out there about what a permissible Normal Retirement Age is. IRC 411(a)(8) says that a plan cannot have a NRA later than 65 & 5.
The plan I am looking at has a NRD that is the last day of the plan year (December 31) in which 65 & 5 is met. So, for someone born on January 1, the NRD would basically almost be age 66 for them.
Typically, plans define NRD as the first of the month coincident with the attainment of NRA. This has the same issue as the one noted above, in that someone born on the 2nd day of the month would have a NRD that is almost at age 65 1/12 and someone born on the first day of the month, the NRD would be 65. But this doesn't feel as unfair as the example above, where the NRD is practically at age 66.
What restrictions are there on NRD? This might be a dumb question, but I've never had to think much about it since all the plans I've seen before have a NRD that is close to NRA.