On the credit memo, use the same item that  you used on the original invoice Рthis will show no change on your cash basis P & L.

Resolution for 'basis P L. issue: 'apply credit memo' available: Yes.

The basis P L. issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the basis P L. issue yourself by looking for a resolution described in the article. If it is a complex basis P L. issue or you are unable to solve the issue, you may contact us by clicking here or by using other basis P L. support options.

For more information about resolving issues related to basis P L. in Quickbooks/QBO or to get support for the issue 'apply credit memo', click the link below: