Question:
How to calculate my income tax for the current FY 2005-06? I am a senior citizen.?

Answer:
If u have already computed ur total income for the year and given the Deductions u r eligible for under Chapter VI A (normal deductions for investments etc.) then u can calculate ur income tax a under:
Senior citizens are eligible for a basic exemption limit of Rs. 1,85,000 from their Total Income. U need to pay taxes only on the amt exceeding 1,85,000.
The rates of taxes are:
For 185000 to 250000 rate of tax is 20%
For above 250000 rate of tax is 30%

If ur income is 300000 then on Rs65000 u will pay 20% and balance 50000 u will pay 30%.

Also, if ur total income exceeds 10,00,000 then a surcharge of 10% of the gross tax computed as above is payable..

This will be of help to u if ur return and income is simple but if it is complicated having many sources then i guess u'll need professional help.