Tenants Did not pay Deposit

[Xela Batchelder]

I'm taking over a building and leaving the tenants in the space.  They are all long term tenants (newest is 2 years).  The leases are now month to month.  They said they have not given any security deposits or similar.  If you were taking over a place, would you now charge your tenants' security deposits?  And if so, how would you do this?  Slowly over a few months?  I'm already planning on raising rents closer to Market rates over the next 2 years, so they will already be getting some increases.