When QuickBooks direct deposit not working is a problem, it can disrupt payroll processing. Common causes include incorrect bank details, insufficient funds, outdated QuickBooks software, or issues with the Intuit Payroll Service. To resolve this, verify and update bank account information, ensure funds are available, and update QuickBooks to the latest version. Additionally, check the status of direct deposit transactions and contact Intuit support if needed. Regularly monitoring payroll setup can help prevent future issues.