Under 415, there is no credit for a YOP when a plan is frozen because the Participant cannot accrue a benefit (i.e., participate) when the plan is frozen. It's a different story if the plan is active, but the participant does not earn an increase in their benefit, for example, a formula of $100 x YOP up to 3 YOP. In year 4 the Participant will earn a YOP if the required hours were worked for 415.