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Marlin GTX help

Point-of-sale and business management for tyre and mechanical workshops.

Credit Notes BT

Learn the basics about Credit Notes in Marlin GTX trusted automotive software by Megabus.

Updated 30 October 2026

**Marlin GTX** enables customer credits and invoice reversals to be processed using credit notes.

Credit notes can be added manually to apply adjustments, or automatically generated by reversing an existing invoice.

All credit notes can be processed using the Invoices module.

The module can be accessed by selecting Main > Data Entry > Invoices from the menu bar..

Screenshot from the Credit Notes BT help article

Adding Credit Notes

Credit notes can be added by clicking on the Credit Note button on the left.

Screenshot from the Credit Notes BT help article

In the Enter Credit Note window:

  • Select the Salesperson
  • Add products and values using the Line Details list
  • Click Finalise at the top

Reversing Invoices

Main > Data Entry > Invoices > Credit Note

Invoices can be reversed by loading the original invoice details into a credit note.

Help centre screenshot

To reverse an invoice:

  • Select the Customer
  • Click the Invoice Reference picker
Help centre screenshot

In the Select Invoice window:

  • Select the original invoice at the top
  • Review the Transaction Details below
  • Ensure the required line items are ticked
  • Click Select

The invoice details can be added to the credit note and the credit note can then be finalised as usual.

Tip — To insert the full credit amount into a payment type field, click the field and press Enter

::: (Warning) (For Further Details) See the Customer Credit Notes{target=_blank} help guide. :::