I was married in April, but my work didn't change my tax "status" to married until December (just an overlooked error on the HR dept). Do i file single, or married?

[AnnaB · Accepted solution]

If you were married as of December 31, then you must file as married (either jointly or separately), unless a special circumstance applies regarding separation.

Your status at work generally only impacts your withholding from your check (reported on Form W-2) as far as taxes go.  Not to mention, it is perfectly fine for you to still withhold as a single person which will yield more tax withheld and a bigger refund or lower balance due.