For purposes of determining filing status, which of the following is not a requirement for a married taxpayer to be treated as unmarried at the end of the year?
1) The taxpayer's spouse did not live in the same household as the taxpayer for the last 6 months of the year
2) The taxpayer paid more than half the cost of keeping up a home for the year
3) The taxpayer's spouse did not file a joint return for the year
4) The taxpayer's spouse did not have any gross income for the year