You can enable subtotal with tax in Moon Invoice easily by following the steps below.

1. Open the Moon Invoice application on your device or tap on this link.
2. From the Dashboard, click the Settings icon.
3. Navigate to App Settings ➜ Invoice.
4. Under Summary, select Subtotal with Tax (set to Default by default).
5. Choose Yes or No based on your preference.
6. Finally, click Save to apply the changes.