In the realm of 401k plans, probably, since some 401k plan companies prefer plans with at least 100 employees. Being a smaller company may limit the number of 401k plan companies that the employer can choose from.
There’s a large gap between, “I want to get my money working for me sooner, and this sounds unethical”, and, “I caught my employer doing something illegal and I want to make a windfall by reporting them”. And if it’s the second scenario, I would suspect that it might be challenging to explain that one to future potential employers.
The OP said he’s worried about getting fired–that the company will find an excuse to get rid of him if he speaks up. I’ve worked with that kind of fear and it’s not fun.
Plans with over 100 participants complete a much more extensive Form 5500 and require an auditor’s statement. No such requirement for small plans, except for small traditional pension plans, which require actuarial certification.
But small plans still need to remit ee contributions in a timely fashion. That’s the point here.
I think the first thing I would do is see if I can get insight from other employees. Everyone who is affected by this notices, someone else has probably asked. It makes me wonder if the company is having a hard time paying their bills.
Regardless, I would keep my eye out for another job, because whether you decide to report them or not, it doesn’t sound like a business that will be around for long. I would stop investing in their 401K, and invest in a Roth on my own. I wouldn’t trust them with my money. If they go under, who knows how long it will take to get your $$ back.