Let's start with the QuickBooks Online Unapplied Cash Payment Income account. How can one achieve balance? What are the reasons for this?
This account usually appears when a customer payment is received before the invoice date. When this happens, QuickBooks will charge an amount to the unapplied cash payment income account.
It can also happen if a customer payment and an invoice are not reconciled.
When you convert QuickBooks desktop to QuickBooks Online, you may also notice unapplied cash payment income. This could be the case if journal entries were utilized to amend accounts receivable in QuickBooks desktop.
Another probable (though uncommon) cause, according to the QuickBooks support website. A bank account type can be matched to a product or service item on an invoice. This will result in the money going into unapplied cash payment income before it is ever paid. To avoid this, make sure the product or service is associated with an income account type.