Is Golden Parachute rule based on 1 payment or annual payments?

Is the 3x limit over base compensation the total limit for any severance pay or the annual limit? It’s worded somewhat ambiguously although I assume it’s the total limit.

So if base pay is $1mm, and the person gets paid $2.0mm in year 1 and $1.5mm in year 2, only the extra $0.5mm would be subject to excise tax / non deductibility?