Correction for failure to implement Roth deferral election correctly

[Spodie]

Payroll was not basing the deferral election percentage on Gross Pay, but rather the Net Pay for the Roth contribution. Taxes were calculated correctly using Gross. Result is the Roth contribution is less than what was elected on the deferral election. Goal for the participant was to have the same contribution amount for pre-tax and Roth.

Example:

Gross Pay $1,000

Roth Election 4% ($40)

Taxable Income $1,000

Fed w/holding (15%) $ 150

Net pay $850 - This was used to determine the Roth Deferral of $34 (short by $6)

I'm confident that the result is a "missed deferral opportunity" and can be corrected with EPCRS. Where I'm hazy is what the corrective QNEC contribution should be? It is a 09/30 plan year so the plan year is almost over so there is definitely less than 9 months left in the plan year, so that option is out. So, the only other option is the corrective QNEC.

Rev. Proc. 2013-12 states that the corrective QNEC for after-tax contributions is 40% of the missed deferral, 100% of any missed match and of course plus earnings.

The relaxed corrections with 2015-28 do not seem to apply to after-tax contributions. Can anyone tell me otherwise and point me in the direction of any guidance that has been issued by the IRS of the appropriate corrective QNEC for after-tax contributions?

Thank you!