Increasing value security deposit to incentivize good tenantry

[Tracy Tippett]

Has anyone ever set up a increasing value security deposit that builds for the tenant and can be cashed out when they depart without arrears or damage. IE: adding 25-50 dollars to the value of the security deposit each time rent is paid on time. After a tenancy of 3 years at 25.00 per month their security deposit would be 900.00 larger then when originally collected.

I imagine that a cap of a few thousand would be a good idea.

Are there any legal pitfalls here?