When would I have uncollected Social Security and Medicare Taxes?

In certain situations, your employer may consider you to be an independent contractor and issue you a 1099-MISC while the IRS may determine that you should have received a W-2. In situations like this, you may need to pay Social Security and Medicare taxes on those wages. 

Go to this section in Credit Karma Tax: Uncollected Social Security and Medicare Tax on Wages

You may have to report uncollected Social Security and Medicare Taxes on wages if any the following applies to you:

• You performed services for a company where you were classified as an independent contractor and you should have been classified as an employee.
  
• You received a W-2 and a 1099-MISC from the same company in the same year and the income listed on the 1099-MISC should have been classified as wages.
  
• You received a notice from the IRS stating that you should have been considered an employee or are waiting for a reply to confirm you’re an employee.
  
• You filed Form SS-8 with the IRS.
  

If you owe Social Security and Medicare taxes due to tips you received that weren’t reported to your employer to include on your W-2, you should include this in your return using Unreported Tip Income instead.