Plan coverage change during testing year

[Guest jae3207]

2005 Calendar year plan using current year testing methodology.

Company A & B are owned 100% by the same person and are all covered under one 401(k) plan.

On 9/30 Company A is sold (equity interest) 100% but continues to sponsor the current plan. Company B is spunoff into its own plan as of 10/1.

Question: Can we test Companies A & B as separate plans, due to the coverage change or do we have to included Company B's employees up through 9/30?