Any limits on auto enrollment/auto increase?

I know there is a 10% limit for the first year, and a 15% limit for all subsequent years, on automatic contributions under a QACA.  However, if you have just a straight auto enrollment/auto escalation (not an EACA or QACA), are there any legal limits on how high the level of contributions can be?  I'm not finding any, but proving a negative is always hard.

I'm not aware of one either as a matter of qualification. Other than for QACAs, our pre-approved plan documents do not have any stated maximum or notes in the blanks indicating an upper limit on either auto-enrollment or auto-escalation.

I would think at some point you would run up against a practical (or possibly fiduciary?) limit if you tried to auto-enroll everyone at, say, 75% of compensation and then had to take affirmative elections from everyone anyway (and/or field irate phone calls from people who weren't paying attention and had their entire paycheck deferred). 

Agreed. IRS Notice 2009-65 sample amendment for a non-EACA doesn't include any limitations either.

https://www.irs.gov/pub/irs-drop/n-09-65.pdf

If ERISA governs the retirement plan, “[t]he Secretary [of Labor] may prescribe regulations which would establish minimum standards that . . . an [automatic-contribution] arrangement would be required to satisfy in order for [ERISA § 514(e), preempting States’ laws] to apply in the case of such arrangement.”

But the rule is 29 C.F.R. § 2550.404c-5, which sets conditions for notices and for a qualified default investment alternative, but does not otherwise specify “minimum standards”.

Two practical points:

EBECatty suggests a too-high implied-assent rate might lack a participant’s consent and attract an opt-out.

Beyond that, another practical point is considering all possible wage reductions and deductions.  For example, a retirement plan’s sponsor might set the highest implied-assent contribution so it would not interfere with withholding for Social Security taxes and Federal, State, and municipal income taxes and also would not interfere with participant contributions for health coverage, a health flexible spending account, a dependent care account, and other welfare benefits.

For a lower-wage worker, the amounts for some of those arrangements might be relatively big percentages of pay, and so might leave smaller portions of pay available for retirement contributions.

I don't see a point in setting the auto enroll percentage too high.

If I ignored the correspondence and all of a sudden had 10% taken out of my pay I might be like "heck with that, stop it right now."

But if only 3% came out, I might be like "Hmmm, that wasn't too bad..."