What happens if you don't report all wages to ssdbut get a 1099?

The IRS gets a copy of your 1099 forms the same as you do. For this reason, when they get to the task of matching up forms and returns for the year you received the 1099, the IRS will see that you did not report this income. You will then get a letter along with a bill for the amount you will owe for that tax year plus penalties and interest.