Capital Gains Tax When Selling a Long-Held Carlsbad or Encinitas Home: The Section 121 Exclusion Explained

How Does the Section 121 Exclusion Work?

Section 121 lets you exclude gain from the sale of a principal residence you owned and used for at least two years during the five years before the sale. The limit is $250,000 per person or $500,000 for most married couples filing jointly. You generally cannot use it again within two years.

The statute reads that gross income "shall not include gain from the sale or exchange of property if, during the 5-year period ending on the date of the sale or exchange, such property has been owned and used by the taxpayer as the taxpayer's principal residence for periods aggregating 2 years or more" (26 U.S.C. Section 121(a), via Cornell LII, retrieved October 29, 2026).

IRS Publication 523 (2025), Selling Your Home, "for use in preparing 2025 Returns," walks through the eligibility test, the ownership and use requirements, and how to figure gain (irs.gov/publications/p523, retrieved October 29, 2026).

What If My Gain Is More Than $500,000?

If your gain is more than the exclusion, the excess is taxable. Gain is generally your sale price minus selling costs, minus your adjusted basis, which is what you paid plus qualifying capital improvements. Long-held coastal homes often exceed the exclusion, so documenting improvements and selling costs matters a great deal.

The California Franchise Tax Board states that you may exclude up to $500,000 if you file jointly and meet the ownership and use tests, and that "any gain over $500,000 is taxable" (FTB, Income from the sale of your home, last updated 01/07/2026, retrieved October 29, 2026).

Here is an illustrative example only, not a projection for any specific home. A married couple bought in Encinitas for $600,000, made $250,000 of documented capital improvements, and sells for $2,400,000 with $120,000 in selling costs. Their gain is about $1,430,000 ($2,400,000 minus $120,000 minus $850,000). After the $500,000 exclusion, about $930,000 would be taxable gain. Your CPA will apply the actual federal and California rates to your situation.

Section 121 at a Glance

Is There Still a One-Time Over-55 Exclusion?

No. The old one-time over-55 home sale exclusion was replaced when the Taxpayer Relief Act of 1997 rewrote Section 121, effective for sales and exchanges after May 6, 1997. Today there is no age requirement for the exclusion. Many long-tenured owners still search for the old rule, so it is worth clearing up before you plan a sale.

The current exclusion is not a once-in-a-lifetime benefit. Under Section 121 it can generally be used again as long as you meet the two-of-five-year tests and have not excluded gain on another home within the prior two years (IRS Publication 523, 2025).

If you are 55 or older and buying a replacement home in California, a separate rule, Proposition 19, may let you transfer your property tax base. That is a property tax rule, not an income tax rule. We cover it in our Proposition 19 downsizing guide.

Seller Tax Prep Checklist Before Listing

• Find your original closing statement to confirm purchase price
• Gather receipts and permits for capital improvements
• Estimate selling costs with your agent
• Confirm you meet the two-of-five-year ownership and use tests
• Check whether you used the exclusion on another home in the last two years
• Meet with a CPA before you accept an offer, not after closing

Frequently Asked Questions

Here are direct answers to the questions sellers ask us most about this topic. Each answer is based on the sources listed below, retrieved October 29, 2026. Where a detail depends on your situation, the answer says so, and we are glad to walk through yours in a short conversation.

Does California tax home sale gains differently than the IRS?

The FTB says California generally allows the same $250,000 or $500,000 exclusion. Gain above that amount is taxable by California as well as federally. Your CPA can confirm how state and federal amounts differ for you.

Can I still use the over-55 exclusion?

No. The one-time over-55 exclusion was replaced by Section 121 for sales after May 6, 1997. Section 121 has no age requirement.

Do kitchen remodels count toward my basis?

Capital improvements that add value or extend the life of the home generally increase basis under IRS Publication 523. Routine repairs generally do not. Keep receipts and permits.

What if I rented the home out for part of the time?

Periods of nonqualified use and depreciation can reduce the exclusion or create taxable gain. IRS Publication 523 covers these rules, and this is a case for your CPA.

When should I talk to a CPA?

Before you list, so you can gather records and consider timing. Once escrow closes, most of the planning options are gone.

Sources

• 26 U.S.C. Section 121 and its Effective Date of 1997 Amendment note (Pub. L. 105-34, Section 312(d): applies to sales and exchanges after May 6, 1997), Cornell LII, https://www.law.cornell.edu/uscode/text/26/121 (retrieved October 29, 2026)
• IRS Publication 523 (2025), Selling Your Home, https://www.irs.gov/publications/p523 (retrieved October 29, 2026)
• California FTB, Income from the sale of your home, https://www.ftb.ca.gov/file/personal/income-types/income-from-the-sale-of-your-home.html (last updated 01/07/2026, retrieved October 29, 2026)