Will I owe money to the IRS if I was issued a severance package?

We have no idea.  We cannot see your information or know how much you received in the severance package.  You have to prepare a tax return and enter ALL of your information to find out.  

I have the same question: is a severance package treated exactly the same as compensation for work for tax purposes? do I enter it as an additional W-2 in TT?

Yes, Severance payments are wages subject to social security and Medicare taxes. Your employer will include this amount on your Form W-2 and will withhold appropriate federal and state taxes.

Enter it as an additional W-2.

• Log in your account.
• Select Wages and Income the Income and Expenses.
• Select Review next to Job (W-2)
• On the screen Your W-2 info so far select Add a W-2.