Delay in crediting employee deferrals to retirement accounts has become a popular issue for the Department of Labor during plan audits of late. Generally, the company must deposit employee contributions to the retirement plan as soon as they can be segregated from the employer's general assets. The 15th of the month following the month of the contribution is not a safe harbor ("do this and you'll be fine), it's an absolute deadline. If your employer routinely takes longer than a week, I'd suggest contacting the U.S. Department of Labor's Employee Benefits Security Administration. If you believe your employer would be receptive to discussing the issue, you could also take it up with them.