Claimed a "0" and Single and still owed Federal taxes?

This would best be a conversation to have with the payroll person or person(s) at your employer, but in the abstract it seems unlikely that there would have been no changes to federal tax withholding if your pay increased a few times during the tax year.   The only scenario that I could not see it changing at all is if somehow mistakenly you were exempt from taxes (Certain individuals may be exempt from Federal income tax withholding, such as students, the visually impaired, and those older than 65 whose sole income is Social Security, earned income credit in general) though this has to be renewed annually.  

I would reach out to payroll and ask to verify what your W-4 looks like currently to check what you state it is as well. 

All the best,

Marc T.

TurboTax LiveTax Expert

28 Years of Experience Helping Clients