Service tax impact on credit note for penalty amount hold by customer

Dear Colleagues,

I have query related to service tax . A service provider has raised an invoice for providing services and also giving an assurance for maintaining the quality of material. He raised an invoice for services say Rs. 2 cr + service tax. Now service recipient has raised a claim of Rs 10 lac for quality deterioration. Now please suggest us whether service tax is applicable on Rs. 10 lac credit note on not ? If yes is there any case law ?

Regards

Rakesh Mittal

09643356753