Mistake when restating

[Rai401k]

We took over a plan in 2012 and restated their plan on to our document.

The prior plan document stated that "discretionary bonuses" were excluded from the definition of compensation for ER contributions only.

When we restated we misread stated "bonus" compensation was excluded from ER cont (not specifying discretionary bonuses)

Now that we are calculating the ER contribution for 2012 the client has informed us us that they have a "contract bonuses" that should be included.

Is there a way we can do a retroactive amendment for 2012 to fix the document for 2012 only. (We have corrected going forward) The amendment is not decreasing benefits and the ER contribution has not been funded yet. Is it too late since the plan year is closed?

[Belgarath]

While I'm sure no one on these boards would either do this or recommend it, I have heard stories about TPA's who would do a substitute page, and do a new SPD to be distributed due to an error omitting the includible bonus compensation, the error being discovered in the SPD during a routine review of the language - such paperwork being hand-delivered to the client...

As to a correct method, Revenue Procedure 2013-12.