When I add a job to ContractorTools and sync it with QuickBooks, it creates two customers in QuickBooks: a customer and a sub-customer under the customer. Why?
The reason is because the QuickBooks data model does not support the idea of "jobs", or the idea that the business transactions you have with a customer should be grouped together as a "job". On the other hand, all business transactions (estimates, invoices, change orders, credits, payments, etc.) in ContractorTools are grouped into jobs.
In order to mesh these two different data models, ContractorTools creates a sub-customer under the customer and uses that as the job. All transactions for a job in ContractorTools are attached to the sub-customer in QuickBooks. This makes a few things possible:
Each job in ContractorTools can have a separate job number in QuickBooks.
Multiple jobs for the same customer can be grouped under a single customer in QuickBooks.
Each job can have a different job site address in QuickBooks.