when it comes to the crunch

when it comes to the crunch

When it is critical. Related to "crunch time," which is a critical period of time characterized by a heightened pressure to succeed, usually at or near the end of a given situation or undertaking. Also seen as "when the crunch comes." I know we haven't always been able to rely on him, but when it comes to the crunch, he'll be there. When it comes to the crunch, you better be ready to perform.
See also: come, crunch
Farlex Dictionary of Idioms.

when it comes to the crunch

or

if it comes to the crunch

COMMON If you talk about what you do when it comes to the crunch or what you will do if it comes to the crunch, you mean what you do or what you will do when a situation reaches a critical point. I know when it comes to the crunch, he'll support me and be there for me. If it comes to the crunch, I'll resign over this. Note: You can also say the crunch comes when a situation reaches a critical point. The crunch came when we discovered newly promoted managers were getting more money than we were. Note: You can refer to the time when an important decision has to be made as crunch time. It is crunch time for the future of the society, which is absolutely in policyholders' hands. Note: `Crunch' is the sound used to imitate the sound of something hard being crushed, broken or eaten.
See also: come, crunch
Collins COBUILD Idioms Dictionary, 3rd ed.

when (or if) it comes to the crunch

when (or if) a point is reached or an event occurs such that immediate and decisive action is required. informal
See also: come, crunch
Farlex Partner Idioms Dictionary

if/when it comes to the ˈcrunch

(informal) if/when the moment comes when something must be decided or done, or a difficulty can no longer be avoided: She was always threatening to leave him, but when it came to the crunch she didn’t have the courage.
See also: come, crunch, if
Farlex Partner Idioms Dictionary
See also:
  • if it comes to the crunch
  • if/when it comes to the crunch
  • it's crunch time
  • crunch time
  • a parting shot
  • cut someone some slack
  • cut someone some slack, to
  • lose (one's) train of thought
  • lose train of thought
  • before the balloon goes up