In response to concern over the slowdown in the growth of tax revenues, a service tax audit for telecom companies may soon come into effect. In 2005-06, service tax collections increased only 4 per cent, to Rs 40.9 billion. This is well below the 17.6 per cent growth in the sector's earnings during the same period. The increase in Cenvat credit (credit for the duty paid on inputs) is being considered as the main reason for the deceleration in the collection of tax revenues.