Aishwariya, everyone have replied to you suitably regarding Income Tax. As your cousin is an IT professional, please note that she has to get her accounts audited u/s 44AB if her receipts from profession and or billing exceeds 10 lakhs in an accounting year. This also includes advances received that may not have been billed. Besides this, she has to register under service tax if her turnover in a year exceeds 9 lakhs (for this Act it is money received against her services) and start paying service tax when receipts against services exceed 10 lakhs. Service tax willnot be payable against export of services provided for her service the recepient is outside India and she receives the payment in India in foreign exchange.
No one has thrown light on Professional Tax as it is not a Central Government levy and varies from state to state. Professional Tax is Tax on Employment, Professions, Trades and callings. This is usually levied by State Governments. In some states,they do not levy this tax. In states like Maharashtra, the department is under the VAT (Sales Tax department). In Gujarat, the State Government has committed the revenue from this Tax to the Municipal Corporations and asked them to collect on their behalf from those businesses, professions and employes in their jurisdiction and to use the proceeds for the Corporation. Usually on employment, the employer deducts and pays. Others have to enroll and pay annually according to their activities (VAT dealers, commission agents, insurance agents, professionals, Shop Owners under shops and establishment act, director of company, partner of firm etc., cab owners, rickshaw owners etc.). If you fall under multiple entries (incl. if your tax is deducted on employment), the maximum ceiling currently is Rs.2,500/-). In each head above there will be further rates depending on conditions like turnover for VAT dealers, number of employees for shops and income for others. If you fall under multiple heads, you have to enrol under that head where your rate is the highest. For Rickshaws if they say to pay Rs.x per rickshaw, the highest that is collected is Rs.2,500/-. The ceiling has been fixed by the centre and they may make constitutional ammendments to increase this so that states can shore up more revenues for themselves / their civic bodies as applicable.