This is a good reminder that property software is never just rent collection — the tax rules change with the type of unit, and getting that wrong is expensive. The mixed-use point stood out to me: residential exempt, commercial at 15%, and sales under a different regime altogether means the system has to know what each unit is before it can invoice correctly. Storing that as a unit field, rather than trying to fix invoices after the fact, is the right call. Compliance work like this is invisible when it works, and very visible when it doesn't.