Reports--what do the rpts include

RE: P&L

For each income/expense accounts type account, displays the sum of the transaction detail rows that use the account for the report period.

RE: Sales by Customer Summary

Shows the total by customer for select items, "all sales items", recorded on sales forms (invoices, credit memos, sales receipt, ...) for the report period that use a customer.

• Income not associated with a customer is excluded (sales receipts don't have to have a customer).
• Income not on sales forms are excluded.
• Sales that are not income/expenses are included (for example, you could sell an asset like a car, which is not income).

RE: Income by Customer

Shows the total by customer for all income/expense accounts for the report period.

• So, is really Net Income by customer.
• Income/expenses not associated with a customer are excluded. 

Re: All 3 of these reports give me a different total for earned income.

I don't think any them try to give you anything like earned income, at least not if some of your data that uses income accounts is not earned income.

Thank you so much for taking the time to reply with details. It definitely helps, but still doesn't answer why my totals would be off. I do think it's the way QBs runs reports, or at least that's what I'm concluding.

I think it does. As noted, the reports report on three conceptually different things. They are not designed to be the same.