How does one calculate advance tax?

[ontherocks]

If the only extra income is from Savings and Deposit/FD interest, how does one forecast what his/her annual income at the end of March is going to be?
FDs could be broken, savings could change any any time during the financial year. Is advance tax always a guesstimate?
Do people download the interest certificate from the bank's website in each quarter to get an estimate? What do people do?

 

[SonyTom]

It's an estimate. Even if you pay more, you will get refund