The state that paid unemployment will notify the IRS and let them know that you received unemployment.  The computer will flag your return and any refund will be held up while you are investigated.   

We need to report ALL income from a regular job, side job, freelance work, and any forms of self-employment.  Remember, those 1099's, and W2's are filed with the IRS and if you have not reported or under-reported income there could be fines and penalties accessed to the return.

@Jonjonjlc 

If you received unemployment income and did not report it on your tax return, you will need to amend the tax return and report the income and any tax withheld.

Here are a couple of links that will help you get started with amending your return in TurboTax.

https://turbotax.intuit.com/tax-tips/amend-return/video-how-to-amend-your-tax-return/L2wLEwRf1 

https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return/01/27439