The worksheet on page 11 of the instructions for form 1040-EZ (which, I guess, is what you're talking about) only applies if you have Social Security (or Railroad Retirement) income. If you do, and your income (disregarding Social Security income) exceeds the limit on line 6, you cannot file the -EZ form.
You may only use the 1040-EZ form if you have no dependents, you cannot be taken as a dependent on anyone else's return,all of your taxable income is from wages, at most $1500 of interest and dividends, and unemployment compensation and Alaska Permanent Fund dividends, and you are not eligible for or do not elect to receive any tax credits or itemized deductions.
If your gross income is $45,770, and you are married filing joint, and you can use the 1040-EZ, then your taxable income would be $27,870, and your tax would be $3,679. I can't tell how much you owe, as it depends on how much was withheld.
Are you saying that your income, disregarding social security, is $45,770?
If so, then 85% of your social security benefits are taxable, and you are likely to be in the 15% tax bracket.