In this situation, Tenant Jones paid full rent for the month of June (which is $900) on June 1st, even though they vacated the apartment on June 7th. Since Jones provided a legal 30-day notice to vacate, their tenancy does not officially end until June 30th, meaning they are responsible for rent for the entire month of June.
Tenant Smith moves in on June 16th, but since Jones had already paid for the full month of June and is entitled to that occupancy until the end of their notice period (June 30th), there is no overlap in terms of legal occupancy.
Therefore, Jones will not receive any refund. Jones will have fulfilled their rental obligation for the month of June until the end of their notice period (June 30), and the property manager cannot charge both tenants for the same period.
In summary, Jones receives no refund because they paid the full month's rent for June, which covers their notice period.