Post-Retirement Medical Accounts-DB

[JAY21]

We have a husband and wife plan with no employees that want to fund for post-NRA medical benefits. They still have 10 years before the assumed NRA so as I review some of the summaries available on these medical accounts I'm not sure how to fund for these benefits since they must be "reasonable and ascertainable". Probably the "ascertainable" issue bothers me the most as I'm not sure how future medical benefits are easily ascertained, unless maybe I just fund for the current medical insurance premiums with maybe a COLA assumption (not to exceed the 25% aggregate cap). I'm assuming the discrimination rules don't preclude them since they have no NHCEs. Does this type of funding typically take an actuarial funding approach or more of a pay-as-you-go approach for only those in retirement ? From the limited info I've provided can anyone suggest whether it's even reasonable to continue to pursue and research this, or am I'm blown out of the water for some reason from the limited facts given.