Nla Tenancy Agreement 2019

I just opened an account with my chosen rental bond system, so the deposit can be paid by the management agency that looked after the property, but the management company says I have to repay part of the deposit to the tenant under the new legislation. Is this correct, since the tenant took over the property in 2016 before the legislative changes, so nothing has really changed? However, all new leases from 1 June 2019 must comply with the rules. . . .