How we can take the impact of negative lines (Advance deduction)?

XML and business rules
1

When we start a Project, normally client pays us in Advance as a part contract.
After that when we issue progress invoices, a portion of the advance is deducted from each progress invoice as an advance recovery, so the client pays us net of advance.

As per Law, the treatment of VAT should be like this

Progress invoice 100 x15 15 As per the Fatoora Portal, this positive line was accepted and reflected there.
Less: Advance recovery -10 x15 -1.5 But this negative line is not accepted by the Fatoora Portal, due to which we can’t take the effect of this negative line (e.g. Advance recovery) in the Fatoora Portal and in QR Code,

Net value invoice after Advance recovery 90 13.5

Question:
How we can take the impact of negative lines (Advance deduction) from each invoice in the Fatoora portal and in the QR code if the negative line is not accepted by the Fatoora Portal

2

In given example, amount of SAR 11.5 can be adjusted from progress invoice using the UBL tag cbc:PrepaidAmount (BT-113) provided that a Tax Invoice was issued at the time of receiving advance.

For understanding how to adjust the VAT that was already paid through Advance Invoice (prepayment invoice), kindly refer Section 8 of the Detailed E Invoicing Guideline (link provided below) Detailed E Invoicing Guidelines