If you are a property manager, you sometimes end up taking over someone else's tenants.  Maybe another property manager has closed their business, or a property owner is not happy with their current managers performance. 

When you take over someone else's tenant, they will most likely have a positive or negative rent balance at change over date.

One option is to create the tenant with the start date being the date the tenant first moved into the house, and then go back into the rent periods screen and zero out the rent owing from all previous rent periods so that the total balance owing to you is correct.

Another option is to create the new tenant with the tenancy start date as the date you are taking over the tenancy. Then go to the rent periods screen, and edit the first rent period and change the rent due amount to be the rent due for that period, plus any balance owing at the tenancy take over date.