Autotask can produce invoices with negative line items, this could be to represent a credit for the cancellation of a service or an adjustment of a subscription. While these negative values show without any issue on the Autotask invoice, Sage Accounts does not like these values. Sage Accounts prefers all credit/negative value lines to appear on a credit note, and charges to appear on an invoice.
AT2Sage handles this by removing any negative values from the invoice and creating a separate credit note for those items. This could mean that one invoice from Autotask is sent to Sage Accounts as one invoice and one credit note.
AT2Sage relies on Sage Accounts to produce the credit note number, Sage will produce this by selecting the next consecutive number from the value stored in:
Sage Accounts > Settings > Invoice and Order Defaults > Options > Credits start from
While for most users this will not cause a problem, users who select to use Autotask invoice numbers for invoices should be aware that the number Sage Accounts produces for the credit note may clash with an invoice number you produce in Autotask.
To reduce the risk of a clash we recommend that you change the value in the ‘Credits start from’ box to be a number that is far out the range that you use for your Autotask invoice numbers.
Alternatively using Sage generated invoice numbers for invoices and credits will remove the risk of a duplicate invoice number being used, you can set this by going to:
AT2Sage > Tools > Options > Sage > Use Sage Invoice Numbers