You will need to provide more details about your question.
In general, everything of value that an employer gives you in return for your services is considered taxable income and should be reported on your W-2 and is subject to withholding of income tax and employment tax (social security and medicare tax).
Most of the time, this include housing. If the employer provides you free or reduced price housing, that is also included in your taxable income. There are a few cases where housing might not be required to be included as taxable income.
We need to know more about your situation before we can answer your question.
Any chance that your and/or your spouse are living/working outside the US? Or do you have an entry on box 14 on your W-2 that matches the amount of the housing assistance?
Otherwise, help xmasbaby0 and Opus 17 to help you by describing your situation in more detail.