What should be kept in mind while making payment of tax ?
While making payment of tax, apart from other things, one should clearly mention following details :

Head of payment, i.e., Corporation Tax/Income-tax (other than companies)
Amount and mode of payment of tax
Type of payment [i.e., Advance tax/Self-assessment tax/Tax on regular assessment/Tax on Dividend/Tax on distributed Income to Unit holders/Surtax]
 Assessment year – this is a general error that assessees commit as AY is different from Financial year
The unique identification number called as PAN [Permanent Account Number] allotted by the IT Department.
The details are displayed on screen and should be confirmed before proceeding with payments.