Sales Tax in differnent GL account for expired goods or 6 months old sales.

Dear Experts ,

I am having requirement , to post sales tax in different GL account at the time of sales return for following cases:

1. If sales return made after 6 months of original invoice.

2. If Goods are expired .

we are using same sales docuemnt type for sales retun if goods are returned before 6 months . What would be the best possible option to achive this requriment.

Thanks in advance

TKG