can we file tax return till march 2011 for AY2010-2011

If an individual is not required to file IT Return (i.e Income is below exemption limit) during the FYr. 2009-10 but files return after 31st March 2011. Will he be penalised u/s 271F?

Yes u can file I T Return for the assessemnt year 2010-11upto 31.12.2012. As there is no tax liability due to  the income being below taxable limits there is no penalty u/s 271F of the I T Act 1961.