This deduction may make the payslip total ($0.00) negative

This warning is displayed as the paylsip may not be able to be uploaded if the total is negative.

This depends on a number of factors, so is just a warning and can be ignored in many circumstances. However, if the default values combined with the lines being uploaded would cause the total to be negative Xero will not allow it to be uploaded and an error will be shown after the upload is attempted.

If the upload fails, either: remove any deductions being uploaded as they are likely what is causing the negative total create an UnScheduled Payrun (which allows negative totals) and assign the user to it before uploading the adjustments.