Prepayment TDS

hello

We have a situation where we do give Prepayment to Supplier -total prepayment amount includes basic + GST Amount. We do not want to deduct TDS on GST portion amount. We create 2 lines in Prepayment invoice for- Basic Amount & GST Tax separately and apply TDS section only on Basic Value line. On receipt of invoice TDS is applied on basic Value line. On prepayment apply , system throughs error for GST portion line in prepayment as it does not carry TDS deduction amount and this amount remains unapplied. How to achieve this ?

Thanks

Gobind Ahuja