The IRS has released an Internal Memorandum discussing the feasibility of adopting a Discretionary amendment after the close of a plan year that increases contributions for the prior year.

Document Excerpt

This Interim Guidance provides direction to EP Determinations and Examinations employees reviewing a discretionary plan amendment adopted within the first 2-1/2 months after the end of a plan year that increased accrued benefits retroactively based on service for that prior plan year. We understand that this type of plan amendment is frequently adopted in conjunction with an Internal Revenue Code (IRC) § 412(d)(2) funding election. In light of the end-of-plan-year deadline for discretionary plan amendments provided in section 5.05(2) of Rev. Proc. 2007-44, EP employees have asked whether these plan amendments are permitted.
This is not a pronouncement of law and is not subject to use, citation, or reliance as such. Nothing in this interim guidance shall affect the operation of any other provision of the IRC, regulations, or guidance thereunder.

Link
https://www.irs.gov/pub/foia/ig/spder/TEGE-07-1215-0026.pdf