Installment payment term with full tax in one installment

Hi,

I have a requirement where customer is looking for a payment term which is like this

1. X% of invoice amount + 100% VAT amount due to XX days

2. rest of invoice amount due in YY days (No Tax)

We can have a payment term with 'Installment Payments' to get the installements but I am not able to deal with Tax amount separately. Like I am able to do X% of (Invoice +Tax) in XX days and (100-X)% of (Invoice +Tax) in YY days, which is incorrect.

I would appreciate if you could help me with this requirement.

Regards,

Harpreet