Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Can my employer limit my maximum 401k contribution amount (below the IRS limit)?
Highly Compensated Employee Rules Aim to Make 401k's Fair would be the piece that I suspect you are missing here.  I remember hearing of this rule when I worked in the US and can understand why it exists.  A key quote from the article: You wouldn't think the prospect of getting money from an employer   would be nerve-wracking. But those jittery co-workers are highly   compensated employees (HCEs) concerned that they will receive a refund   of excess 401k contributions because their plan failed its   discrimination test. A refund means they will owe more income tax for   the current tax year. Geersk (a pseudonym), who is also an HCE, is in   information services and manages the computers that process his firm's   401k plan. 401(k) - Wikipedia reference on this:  To help ensure that companies extend their 401(k) plans to low-paid   employees, an IRS rule limits the maximum deferral by the company's   "highly compensated" employees, based on the average deferral by the   company's non-highly compensated employees. If the less compensated   employees are allowed to save more for retirement, then the executives   are allowed to save more for retirement. This provision is enforced   via "non-discrimination testing". Non-discrimination testing takes the   deferral rates of "highly compensated employees" (HCEs) and compares   them to non-highly compensated employees (NHCEs). An HCE in 2008 is   defined as an employee with compensation of greater than $100,000 in   2007 or an employee that owned more than 5% of the business at any   time during the year or the preceding year.[13] In addition to the   $100,000 limit for determining HCEs, employers can elect to limit the   top-paid group of employees to the top 20% of employees ranked by   compensation.[13] That is for plans whose first day of the plan year   is in calendar year 2007, we look to each employee's prior year gross   compensation (also known as 'Medicare wages') and those who earned   more than $100,000 are HCEs. Most testing done now in 2009 will be for   the 2008 plan year and compare employees' 2007 plan year gross   compensation to the $100,000 threshold for 2007 to determine who is   HCE and who is a NHCE. The threshold was $110,000 in 2010 and it did   not change for 2011. The average deferral percentage (ADP) of all HCEs, as a group, can be   no more than 2 percentage points greater (or 125% of, whichever is   more) than the NHCEs, as a group. This is known as the ADP test. When   a plan fails the ADP test, it essentially has two options to come into   compliance. It can have a return of excess done to the HCEs to bring   their ADP to a lower, passing, level. Or it can process a "qualified   non-elective contribution" (QNEC) to some or all of the NHCEs to raise   their ADP to a passing level. The return of excess requires the plan   to send a taxable distribution to the HCEs (or reclassify regular   contributions as catch-up contributions subject to the annual catch-up   limit for those HCEs over 50) by March 15 of the year following the   failed test. A QNEC must be an immediately vested contribution. The annual contribution percentage (ACP) test is similarly performed   but also includes employer matching and employee after-tax   contributions. ACPs do not use the simple 2% threshold, and include   other provisions which can allow the plan to "shift" excess passing   rates from the ADP over to the ACP. A failed ACP test is likewise   addressed through return of excess, or a QNEC or qualified match   (QMAC). There are a number of "safe harbor" provisions that can allow a   company to be exempted from the ADP test. This includes making a "safe   harbor" employer contribution to employees' accounts. Safe harbor   contributions can take the form of a match (generally totaling 4% of   pay) or a non-elective profit sharing (totaling 3% of pay). Safe   harbor 401(k) contributions must be 100% vested at all times with   immediate eligibility for employees. There are other administrative   requirements within the safe harbor, such as requiring the employer to   notify all eligible employees of the opportunity to participate in the   plan, and restricting the employer from suspending participants for   any reason other than due to a hardship withdrawal.