|Image Source MGN|
NOTE: Comments at this post have been maintained from previous discussions on this topic at "Small to feds" in the interest of demonstrating the often complex and confusing nature of the clearances process.
As one anonymous commentor (not published due to anonymity) pointed out, some of the published comments are wrong and ill advised. It pays to read the latest issue of the NISPOM, linked above.
The anonymous commentor also maintained that clearances no longer cost the company. I do not agree. The indirect costs of maintaining training programs to keep company and individual clearances is an ongoing tangible cost that must be planned for. The government considers that cost allowable through the overhead on contracts, much the same way they are now considering a similar allowability for cyber-security certification.