Yes, all income is taxable so it would need to be included on your return if you have a filing requirement.

But, if that was your ONLY income for the year, then you may not actually need to file a tax return at all.  This is likely what your employer was referring to because you are allowed a certain amount of income "tax-free" depending on your filing status.  However, the problem becomes when you have other sources of income in addition to this income because it is your total income that matters.  Read these two articles below - the first one is for general taxpayers and the second is for dependents.  

https://ttlc.intuit.com/replies/3302274

https://ttlc.intuit.com/replies/3302185

Note:  While you may not be required to file a federal return, you may still need to file a state return as their requirements can differ from federal.  You can view this article for more information about state filing requirements.

https://ttlc.intuit.com/replies/4801660