Plan doesn't permit QNECs

I swear I've seen something from the IRS that states that a plan does not need to be amended to permit QNECs just to use the standard corrections for missed deferral situations that generally involve a corrective QNEC.  In fact, I thought it was right in the EPCRS Rev. Proc.  However, I can't seem to locate anything that confirms my recollection.  Can anyone point me in the right direction (or, alternatively, discredit my memory)?

I think it's going to be in your basic plan document, in terms of what contributions are permitted - and in this case I'm referring to different types of QNEC.
 

Our document vendor had it at one point that a boring X% to everyone QNEC was always permitted to fix a test.  But if you wanted to target the QNEC, the adoption agreement had to have the box checked off providing for QNECs in general

Thanks Bri...  I know that if you're using QNECs to fix testing (whether through EPCRS or otherwise), the plan has to provide for it.  (See, e.g., Section 4.05 of Rev. Proc. 2019-19.)  However, I could have sworn that the IRS has stated that you can implement the corrections for missed deferrals under EPCRS (which involve QNECs) without having to actually amend the plan for to permit QNECs.  I still have yet to locate that guidance though, so perhaps I'm just mistaken.

Section 4.05(2) of Rev. Proc. 2019-19 (aka "EPCRS"):

(2) Availability of correction by plan amendment in SCP. SCP is available for corrections made by plan amendment, as provided in section 4.05(2)(a), (b), and (c). In addition, a Plan Sponsor may adopt a plan amendment to reflect corrective action. For example, if the plan failed to satisfy the actual deferral percentage (ADP) test required under § 401(k)(3) and the Plan Sponsor must make qualified nonelective contributions not already provided for under the plan, the plan may be amended to provide for qualified nonelective contributions.

This is helpful - thanks!