What governs rounding of the EBAR or Employee Benefit Percentage for Average Benefits testing purposes? Is there a requirement? I haven't found one.

Me, neither. The only rounding rules I've found are:

1) HCE counting for 20% rule (can round up, or down, as long as reasonable)

2) 410(B) ratio-percetnages (1.410(B)-9), must use percentages to two decimal place accuracy. (1/100th of one percent)

3) ADP/ACP by participant are also rounded to two decimal place accuracy (1/100th of one percent)

Thanks again, Mike. I hadn't noticed the Ratio Percentage definition in 410(B)-9. I guess that provides a little guidance.

I suppose the argument for three places is found under the rules regarding permitted disparity. see adjustment tables 1.401(l)-3(e)(3)
e.g. is SSRA is 67 and the benefit starts at 68 then the adjsutment is .825, which is to three places.
if you were to impute disparity in testing, it would logically follow you would use 3 places. of course you are talking logic and regs, but still...

It just so happens that the test that prompted this question passed using 3 decimals but failed using 4! It was the 70% average benefits ratio part of the 401(a)(4) test.

It's a little too iffy for me considering the 4 decimal ratio percentage cite, but it's interesting and potentially useful information nontheless.

And yes, the 3 decimal pass was after all the tweaking I could think of.

AndyH-

If it will make you feel any better, I had a plan that failed the nondiscriminatory classification test by 5/10,000 ths of an employee.