Not true that there is NO capital gains tax. You get an exemption, depending on your marital status (single or married). Any profit over that exemption amount is subject to capital gains tax.
From the IRS website:
"If you have a gain from the sale or exchange of your main home, you may be able to exclude from income all or part of the gain.
This exclusion, up to $250,000 for individuals and $500,000 for married taxpayers filing joint returns, is allowed each time that you sell your main home, but generally no more frequently than once every two years.
To qualify for this exclusion of gain, you must meet ownership and use tests.
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Ownership Test: During the 5-year period ending on the date of the sale, you must have owned the home for at least 2 years.
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Use Test: During the 5-year period ending on the date of the sale, you must have lived in the home as your main home at least 2 years.
If you and your spouse file a joint return for the year of the sale, you can exclude the gain if either of you qualify for the exclusion. But both of you would have to meet the use test to claim the $500,000 maximum amount."
Full page is here:
Sale of Your Home