How do you help a financially irresponsible soldier?

I'm trying my best to juggle personal tasks and my soldiers but it's been tough being able to focus on both. It seems I'm always missing something. I currently have three soldiers and one of them is damn near broke a week after payday. He's E-4, makes around $930 after taxes/TSP every two weeks. We've been through a company finance class, in-office class and the SM has had a visit with the finance CTR in our unit all within the past six months. Somehow he ends up with no money before his next paycheck... I have counseled him on managing his finances and to write a report on what he spends once a week but I somehow feel he's not telling me the truth. That he's lying about what he's really buying or paying for.

Being a fresh NCO, I'm still not sure of my limits when it comes to finances nor am I the type to get into one's financial privacy thus why I trusted him to write me an accurate weekly report. However, something isn't adding up and I would like to get to the bottom of it. If it's really necessary I don't mind taking a look at his bank statements and view his credit card statements over the past few months so that I can come to my own conclusion. Is that allowed or stepping over the line?

He only told me of his balance when I asked the other day, during his monthly counseling beginning of the month he was fine. No expensive car, no major purchases that I've seen...