My friend had paid self assessment tax for AY 2012-13 on 31/07/2012.Mistakenly, he entered AY in the challan as 2011-12 instead of 2012-13.The income tax dept has raised a demand.Please let me know how to rectify the AY in the challan.26AS shows the tax credit in the AY 2011-12 which is actually for AY 2012-13.