Configure Invoice Immutability

By default, WHMCS ensures that non-Draft invoices are immutable, and you cannot edit an invoice after it leaves the Draft status. Instead, the system generates credit and debit notes to record adjustments. The Invoice Immutability setting lets you choose from several compliance states.

Disabling invoice immutability can make your accounting records inaccurate. We strongly recommend that you update your business’s workflows to eliminate the need to edit non-Draft invoices. For examples, see Adapting Your Workflow.

Configure Invoice Immutability

To choose a compliance state:

1. Go to the Invoices tab in General Settings.

Go to the Invoices tab at Configuration () > System Settings > General Settings.

2. Find the Invoice Immutability setting.

Find the Invoice Immutability setting.

The system selects Full compliance (immutability enforced, billing notes generated) by default.

3. Select a compliance state.

Select from the following options:

OptionInvoice ImmutabilityCredit and Debit NotesDescription
Full compliance (immutability enforced, billing notes generated)EnabledEnabledYou cannot edit non-Draft invoices. The system generates credit and debit notes to record invoice adjustments.
Immutability disabled (billing notes still enabled)DisabledEnabledYou can edit non-Draft invoices, including their line items, attributes, and notes. The system still generates credit notes and debit notes and applies them to invoices.
Immutability and billing note generation disabledDisabledDisabledYou can edit non-Draft invoices. The system’s other billing mechanisms record adjustments without credit and debit notes. For example, marking an invoice paid records a payment transaction, cancelling an invoice returns money to the client, and overpayments credit the client directly.

4. Confirm your choice.

If you selected an option that disables invoice immutability, click I understand. to confirm your choice.

5. Save your changes.

Click Save Changes.

If You Disable Invoice Immutability

Your invoice immunity setting applies to new and existing invoices. You can edit invoices that the system published before you changed the setting. If you restore full compliance, those invoices become immutable again.

WHMCS also behaves in the following ways:

  • The system displays an Invoice Immutability warning at Configuration () > System Health.
  • The Admin Area displays a warning until an admin dismisses it or you reenable invoice immutability. For more information, see Invoice Immutability Errors.

If you select Immutability and billing note generation disabled, the following behaviors also occur:

  • Moving invoices to the Paid status requires the Manage Invoice permission instead of the Create Credit or Debit Note permission.
  • The system does not change credit and debit notes that it issued previously.
Credit notes may already exist on your WHMCS installation. If you select Immutability and billing note generation disabled, you cannot remove that credit. Reversing it requires a debit note, which the system no longer generates. To remove the credit, you must select an option that allows credit and debit note generation. Remove the credit, then return to the compliance state you want.

Restore Full Compliance

To enforce invoice immutability again:

1. Adapt your workflows.

Update your business’s workflows to eliminate the need to edit non-Draft invoices:

2. Select full compliance.

Go to the Invoices tab at Configuration () > System Settings > General Settings. Then, select Full compliance (immutability enforced, billing notes generated).

3. Save your changes.

Click Save Changes.

This resolves the Admin Area message and the System Health warning.

For more information about each compliance state, see Invoices.
invoices credit-and-debit-notes general-settings

Last modified: 2026 October 20