If a transaction has an invoicing rule, an accounting rule is optional.

If a transaction has an invoicing rule, an accounting rule is not allowed.

If a transaction has an invoicing rule, an accounting rule is also required.

Invoicing rules and accounting rules have no effect until Invoices are paid.

Invoicing rules and accounting rules have no effect unless you choose the accrual method of accounting.

Invoicing rules determine when invoices are due. Accounting rules affect how invoices me accounted for