401k plans are required to not discriminate against the non-HCE participants, and one way they achieve this is by limiting the percentage of wages that HCEs can contribute to the plan to the average annual percentage contribution by the non-HCE participants or 3% whichever is higher. If most non-HCE employees
contribute only 3% (usually to capture the employer match but no more),
then the HCEs are stuck with 3%. However, be aware that in companies that award year-end bonuses to all employees, many non-HCEs
contribute part of their bonuses to their 401k plans, and so the average
annual percentage can
rise above 3% at the end of year. Some payroll offices have been known to
ask all those who have not already maxed out their 401k contribution
for the year
(yes, it is possible to do this even while contributing only 3% if you are
not just a HCE but a VHCE) whether they want to contribute the usual 3%,
or a higher percentage,
or to contribute the maximum possible under the nondiscrimination rules.
So, you might be able to contribute more than 3% if the non-HCEs
put in more money at the end of the year.
With regard to NQSPs, you pretty much have their properties pegged
correctly. That money is considered to be deferred compensation
and so you pay taxes on it only when you receive it upon leaving
employment. The company also gets to deduct it as a business
expense when the money is paid out, and as you said, it is not
money that is segregated as a 401k plan is.
On the other hand, you have earned the money already: it is just that
the company is "holding" it for you. Is it paying you interest
on the money (accumulating in the NQSP, not paid out in cash
or taxable income to you)? Would it be better to just take
the money right now, pay taxes on it, and invest it yourself?
Some deferred compensation plans work as follows. The deferred
compensation is given to you as a loan in the year it is
earned, and you pay only interest on the principal each year. Since
the money is a loan, there is no tax of any kind due on the
money when you receive it. Now you can invest the proceeds of
this loan and hopefully earn enough to cover the interest
payments due.
(The interest you pay is deductible on Schedule A as an
Investment Interest Expense). When employment ceases,
you repay the loan to the company as a lump sum
or in five or ten annual installments, whatever was agreed
to, while the company
pays you your deferred compensation less taxes withheld.
The net effect is that you pay the company the
taxes due on the money, and the company sends this on to
the various tax authorities as money withheld from wages
paid. The advantage is that you do not need to worry
about what happens to your money if the company fails;
you have received it up front. Yes, you have to
pay the loan principal to the company
but the company also owes you exactly that
much money as unpaid wages. In the best
of all worlds, things will proceed smoothly,
but if not, it is better to be in this Mexican
standoff rather than standing in line in
bankruptcy court and hoping to get pennies on
the dollar for your work.