Federal witholding tax from payroll
We live in North Carolina. My wife gets paid every 2 weeks from a private investigating firm of which she is the Office Manager. Her last 3-4 payroll checks did not include any Federal witholding tax which is good for us as her take home pay has increased BUT does this mean that she will be owing the IRS when it comes time to file our 2009 Federal tax returns in 2010? We file joint returns as husband and wife. Have the tax tables recently changed? If not, will we be penalized for failing to pay Federal taxes during the year? I (husband) receive a pension and social security income. I'm confused. Can someone please explain if there is some action I should be taking now to prevent owing the IRS?
Thanks so much, Jim