Is it mandatory to state the service tax registration number in the bill of restaurants?

Yes. As per Rule 4A of Service Tax Rules, 1994.

Yes. It is mandatory.

IF SERVICE TAX REGISTRATION NO. IS NOT MENTIONED IN TH BILL AND PARTY IS CHARGING SERVICE TAX IN THE BILL THEN WHAT IS THE CONSEQUENCES OF IT?????

Its necessary to mention the PAN along with Service Tax Registration No on Every Service Invice.

IF Serrvice tax registration number not mentioned on invoice  than it  would create difficulty to next service receiver in claiming cenvat credit ond.r service tax refu