Tenant signed annual lease in Jan 2010, in which it stated that 90 days written notice required to end lease at the end of that term. Lease states "The initial lease period is 1 year from January 1, 2010 until December 31, 2010 and may be extended every year by one more year. The monthly rent is subject to a 5% increase per year. The lessee must give the lessor 90 (ninety) days notice in writing if lessee intends to terminate the lease at the end of the initial lease period." No written notice has been received from tenants to date, but they moved out at the end of April 2011. We advised them that as lease is yearly, they are responsible for rent payment up until such time as we are able to get new tenants.
Their position is that because they didn't actually sign a new lease on Jan 2011, their tenancy is not annual, but monthly from that date on, and therefore they don't owe anything. They haven't even officially terminated the lease. The top of the lease document says "Lease Agreement as per Florida Landlord/Tenant Statues.
I believe these statutes require the tenant to at least cancel in writing with 60 days notice.
Where do I stand as landlord?

The length of the notice doesn't seem to apply here at all. Even if they gave you a 90 day notice the renewal would not run out until 12-31-11, they owe until then or when you find a new tenant. They did sign an old lease that stated "extended every year by one more year" They can't have it both ways. However, you may have to sue to get your money.

This is actually iffy. The problem is the wording "MAY be extended". So a court will have to decide whether not giving the 90 day termination notice was a tacit agreement to extend. I'm not sure they would. They may decide that the lease converted to month to month. However, they can't just vacate without any notice.

I'm not sure what the notice requirement for FL is, but they have to give some notice so they owe rent to at least the end of that notice period. A court will be very likely to award you that much. If you have a security deposit you will be able to apply that towards what they owe.

I see your point but not sure I agree. For the tenant to turn into a month to month he would have/should have given a 60-90 day notice to end the first lease. With no notice given during the first lease the terms should stay in place abd renew for an entire year.