Question about claiming my wife as a dependant on my tax return?

You're confusing forms with your terminology. The 1040 (Income Tax return) has nothing to do with exemptions. You are thinking of a W-4 where you tell the government how many exemptions you are claiming so that they can determine how much tax to take out of your paycheck. On your 1040, you claim dependents. You can never claim your spouse as a dependent, regardless of whether or not they work. If you are considered married on December 31st, you are considered married for the entire year (regardless if you were married in January, June, December, whatever), you have only 2 filing choices: married filing jointly (better choice 98% of the time) and married filing separately (better choice 2% of the time). So, if you filed married filing jointly for 2005, you're all set...there is nothing more you can do. If you didn't for some reason, you should file a 1040-X (amendment) for 2005 and change your filing status. You have 3 years to file a 1040-X from the date you initially file for that tax year.