Professional tax query

HI,

COULD ANY OF YOU HELP ME ON PROFESIONAL TAX CALCULATION..

MY QUERY

1. IS PROFF.TAX IS TO BE CALCULATED ON BASIC SALARY ONLY OR ON GROSS SALARY WHICH INCLUDDES BASIC,DA,HRA,CONV ETC?

2. PROFF.TAX IS WRT CHENNAI. WHILLE BROWING THE CORPORATION OF CHENNAI WEBSITE, IT STATES THAT PT IS TO BE CALCULATED ON AVERAGE HALFYEARLY SALARY AND WAGES AND THE CORRESSPONDING SLAB RATE WILL APPLY.

THANKS IN ADVANCE