How to Legally Deduct Security Deposit (Tenant Uses it as Last Month's Rent)

[Jack Quin]

Hi,

I did not renew my tenant's lease due to frequent late on rent payment. Currently he is late for the last month's rent and it looks like he is thinking to use his one month's security deposit as the last month's rent. How can I deduct security deposit for unpaid rent legally? Should I file eviction now to serve as an evidence of unpaid rent? The house is in Anne Arundel County, Maryland.

Thanks