Pre PPA many small DB plans used the Individual Aggregate funding method - this worked well for the employer who also wanted to see what each participant's share in the cost would be - some doctor groups especially like to be able to see the split since year-end bonus allotments are dependent on the individual's other expenses to the corporation.

Now enter PPA - the target normal cost is automatically earmarked by participant - but what about the Shortfall Amortization Base - that's an (A-B)/(annuity factor) - how would you split that by participant and still be consistent with the year before's IA allocation ?

You might try continuing to calculate the "recommended" contribution based on individual aggregate. As long as the IA "recommended" is greater than the actual required, you should be fine. If they put in more or less, prorate everything based on the IA numbers.

Or, just allocate the shortfall as a percentage of the individual funding targets.