Rs.10 lakhs is the limit of turnover for charging servicetax.Once your turnover exceeds Rs.10lakhs you need to charge service tax in your invoice and collect from customers and remit to government.
Rs. 10 lakhs is threshold exemption limit,,service tax applicable to you continously once you crossed this 10 lakhs limit in any financial year,
Terms and Conditions for availment of threshold exemption as per Notification No. 33/2012 Service Tax- dated 20.06.2012