I am retire and does not live in US during the year 2018. Do I still have to pay for the federal capital gains tax?

Yes, if you're a U.S. citizen or resident. You'll need to report all of your income, whether it was earned in the U.S. or abroad.

Here's how to enter your foreign income:

1. Sign in to TurboTax and select Take me to my return.
2. Click  and search for foreign income.
3. Click the Jump to link in the search results.
4. Answer Yes to Did you Make any Money Outside the U.S.? and follow the on-screen instructions.

If you lived and worked in a foreign country, you might qualify for the foreign income exclusion. We'll ask questions to see if you quality after you've entered your foreign income.