If i write a check at grocery store will it accept my check if I'm on chex system?

It depends on if they use Chex Systems to validate the check or not- not everyone does cause it costs them money. We have a local grocery store that does not use them and we can write a check there. It's not a mom and pop store either, it's a local chain of 8 grocery stores. I also know the Ace by us doesn't use them either.