Generally, your marital status on the last day of the year determines your status for the entire year. If you are unmarried, or if you are legally separated from your spouse under a divorce or separate maintenance decree according to your state law, and you do not qualify for another filing status, your filing status is single.

Generally, to qualify for head of household status, you must be unmarried and not entitled to file as a qualifying widow or widower with a dependent child. You must also have provided more than half the cost of maintaining as your home a household that was the main home for a qualifying person. You may also qualify for head of household status if you, though married, file a separate return, your spouse has not lived in your home during the last six months of the tax year, and you provided more than half the cost of maintaining as your home a household that was the main home for a qualifying child for more than one half of your tax year.

If you are married, you and your spouse may file a joint return or separate returns.

If your spouse died in 2003 and you did not remarry before the end of the year, you may still file a joint return. This is the last year for which you may file a joint return with that spouse.

If your spouse died during 2001 or 2002, you may be able to file as a qualifying widow or widower. To do this, you must meet all four of the following tests:

• You were entitled to file a joint return with your spouse in the year he or she died. It does not matter whether you actually filed a joint return,
• You did not remarry before the end of 2003,
• You have a child, stepchild, adopted child, or foster child for whom you can claim a dependency exemption, and
• You paid more than half the cost of keeping up a home that was the main home for you and that child, for the whole year.

More detailed information on each filing status can be found in Publication 501, Exemptions, Standard Deduction, and Filing Information.