I am a business owner renting a commercial building in RI for the past 8 months with a month to month verbal lease, nothing at all in writing. February rent is paid but as of February 26, I notified the landlord that I am leaving and will be out by March 3. Rent is due on the first of the month. Have I given proper notice to vacate to the landlord? Is it legal for him to take my security deposit and call it rent owed? Please advise... Thanks

Since there is nothing in writing, then what governs here is what is reasonable and customary. What is customary would be at least one months notice. So, if he is withholding your security for the March rent, I believe a court would uphold that if you took him to court over it.

No, you have not given sufficient notice. The way I read Sections 34-18.1-5 and 34-18.1-6, you would have needed to have given notice no later than February 14th in order to move out by February 28th. Since you gave notice on February 26th you would be responsible for rent until March 31st. And yes, the landlord can withhold the rent from your security deposit.

You can read the applicable laws at Chapter 34-18.1 - Index of Sections. In your situation your "term" is one month.

Agree, you will owe for at least March