Some accounting practices, particularly for EU-based companies, require you to use sequential invoice numbers for paid invoices. In most cases, you must also enable proforma invoicing.

Enable Sequential Invoicing #

To enable sequential invoicing:

1. Go to Configuration () > System Settings > Tax Configuration.
2. In the General Settings tab, enable Tax Support.
3. In the VAT Settings tab:
   1. Enable Proforma Invoicing/Sequential Paid Invoice Numbering.
   2. For Sequential Invoice Number Format, specify the format you want to use for numbering. You can also include letters (for example, include your company’s initials and the year to differentiate invoices for each year to create WHMCS2007-{NUMBER}). WHMCS replaces {NUMBER} placeholder with that invoice’s number.
   3. Update the value for Next Paid Invoice Number. This allows you to set the next number to assign to an invoice.
      • Each time a customer pays an invoice, the number increases by 1.
      • You may want to alter the number here if, for example, you remove an invoice or at the beginning of a new year, to start at 1 again.
4. If desired, update the value for Auto Reset Numbering. This determines when WHMCS will automatically reset Next Paid Invoice Number to use for newly-paid invoices. You can set this to Never, Monthly, or Annually.
5. If desired, enable Set Invoice Date on Payment to have WHMCS change the due date of an invoice to the payment date.
6. Click Save Changes.

Enable Proforma Invoicing #

To enable proforma invoicing:

1. Go to the Invoices tab at Configuration () > System Settings > General Settings.
2. Enable Enable Proforma Invoicing.
3. Enable Sequential Paid Invoice Numbering, Sequential Invoice Number Format, and Next Paid Invoice Number.
4. Click Save Changes.

Last modified: June 14, 2024