What situations will disqualify you from getting a security clearance?

If poor money management will disqualify you from a security clearance, why do congress people spend millions of dollars to get a job that pays about 200 thousand a year??

If you want clear and correct answers I recommend you take some time and go talk to your S2/SSO. They should be able to answer all your questions and even help you start the paperwork. But to answer your question no. Just be honest with anything you get asked. If you did drugs in the past then tell them. When you get investigated it really is about will you be honest and do you have any ties to an enemy. The form you will fill out is the SF86. You can take a look at it and even start gathering the information to prepare for when you actually need it. But I still stand by my original answer... See your units S2/SSO.

As others have stated, financial situations could prevent you from getting a clearance, but the biggest thing that will absolutely prevent it is lying. Do not be dishonest with the investigators. Almost anything can be worked out as long as you're honest.