Break even synergies

Hi guys,

How would you factor in contingent payments / earnouts (could be based on revenue target, EBITDA target or any other metric) when doing a break even synergy calculation?

I am looking at a cash + shares deal where some of the consideration is guaranteed at closing and some is deferred (2 to 3 years period).

I would like to check what the deal would be equivalent if it were an all cash deal in the process.

Thanks