Hello Sir,
As per the details provided by you, it appears that you act as bridging gaps between potential clients and doctors and charge a service fee.
In such cases, Service Tax is applicable and it is to charged on the Service Fee which in your case appears to be Rs.500/-.
Hope this clarifies your query.
Please feel free for any further clarifications.
Thanking You.
Regards,
CA Rohit R Sharma
BCOM, CA, LLB - GEN, CERT. FAFP, CERT FAFD.