Tax Years. (Obj. 6) The date a tax year closes is an important date from a taxpayer's point of view because it stops the IRS from assessing a tax deficiency on a closed tax year. It is an important date from the government's point of view because it stops a taxpayer from making a refund claim on a closed tax year.

a. If a taxpayer files her tax return for 2014on April 1, 2015, on what specific date does her 2014 tax year close under the normal closing rule?

b. If a taxpayer inadvertently (mistakenly) omits too much gross income from his or her income tax return, the normal closing of a tax year is extended by three years. What percentage of the taxpayer's gross income must be omitted from his or her income tax return in order for the closing year to be extended? As part of your answer, explain exactly how this percentage is applied