Time to Declare Matching Contribution Percent

I'm not aware of any such requirement. But is there a requirement that non-SH employer discretionary matching contribution percentage be declared by any certain time. My understanding is that this is left to the language of the plan.

Does anyone have any authority on this.

Thanks!

The only thing I'm personally leery of not announcing before the beginning of the plan year is how much to defer to get the full match.  The definition of discretionary is that you get to decide later on, even after year-end.

But imagine if you never had a match, and then March 2019 you decide to do a 100% of 6% match for 2018.  If I was never told to contribute 6% that might sort of make me mad.