I think there is a set number of days before you have to deposit it sometimes it's done between 45 five days to deposit it a small firm is figured by how much work there doing and how many employees the firm has i would say if you have between 1-7 employees thats small and anything 20 up is a much larger firm

I actually called the firm managing my company's 401k once on this very topic, because I wasn't seeing immediate deposits to my account from my check. They informed me that some of their member companies make their deposits to the plan on a monthly basis, even if the amount is withdrawn from employees' checks every week. Some companies deposit every other week, and some weekly. It appears it's totally up to the discretion of the company for whom you work.