What you enter on your W-4 that you give to your employer to have taxes withheld has no bearing whatsoever on the filing status you enter on your tax return. Since you are legally married you can only file as either Married Filing Jointly or Married Filing Separately. You would want to file as MFJ since it is more advantageous from a tax standpoint then filing as MFS. You receive the highest standard deduction of $24,000 if under age 65.
