Capital Gains Tax on Home Down Payments Explained

If you own investments that have appreciated significantly, you already understand capital gains tax. But when you're liquidating that portfolio to fund a home down payment, the tax implications get more complex—and the numbers get bigger.

Most home buyers don't think about capital gains tax when planning a down payment. They don't realize that paying $200,000 down might actually cost $250,000 or more once you factor in what you owe in taxes. This guide walks you through how capital gains tax actually works when you're buying a home, what rates you'll pay, and how it all adds up.

For the broader strategic picture — including financing paths that avoid this tax bill entirely — see our complete guide to high net worth home buyer financing.

The Basics: Capital Gains Tax and How It Works

When you sell an investment that's increased in value, you have a capital gain. The gain is the difference between what you paid for it (your cost basis) and what you sold it for. If you bought a stock for $10,000 and sold it for $15,000, you have a $5,000 capital gain.

Capital gains tax is the tax on that profit. The rate depends on how long you held the investment.

Short-term capital gains (assets held for one year or less) are taxed at your ordinary income tax rate, which can be as high as 37%. Most long-term investors aren't selling short-term, so this usually isn't relevant for home down payments.

Long-term capital gains (assets held for more than one year) are taxed at preferential rates: 0%, 15%, or 20%, depending on your income level. These are much lower than ordinary income rates, which is why holding investments for more than a year matters.

For 2026, single filers pay 0% on long-term gains up to $49,450 in taxable income, 15% from $49,450 to $545,500, and 20% above $545,500. Married filing jointly: 0% up to $98,900, 15% to $613,700, and 20% above. (Source: IRS Rev. Proc. 2025-32, the 2026 inflation adjustments.)

For most high-net-worth investors, that 15% or 20% federal rate is what applies.

But There's More: The Net Investment Income Tax

If you're a high-income earner, there's an additional 3.8% tax you need to account for. This is the Net Investment Income Tax (NIIT), which applies to the lesser of (1) your net investment income or (2) your income above a threshold.

The NIIT threshold is $200,000 (single) or $250,000 (married filing jointly). Unlike the long-term capital gains brackets, these thresholds are statutory and have not been indexed for inflation since the tax took effect in 2013 — they are the same in 2026 as they were the year the law passed. Any income above those levels is potentially subject to NIIT.

So if you're a high-earning professional with significant investment income, selling investments can trigger NIIT. When you combine the federal capital gains tax (20%) with NIIT (3.8%), you're looking at 23.8% federal tax before state taxes.

And Then There's Your State

Here's where it gets really expensive for some people. State capital gains taxes vary dramatically depending on where you live.

California has no separate capital gains tax, but it taxes capital gains as ordinary income. If you're in California and you're in the top state income tax bracket (13.3%), plus 20% federal long-term gains tax plus 3.8% NIIT, your combined rate is 37.1%.

New York state capital gains tax starts at 6.85% and goes up to 10.9% on top of federal taxes. Combined with federal rates, you could owe 33.7% or more.

By contrast, Texas, Florida, and several other states have no state income tax. In those states, a high-income earner would pay roughly 23.8% combined (federal long-term capital gains plus NIIT).

The state you're in when you sell matters enormously.

Putting the Numbers Together: Your Actual Tax Rate

Let's build a concrete example to see how these layers stack up.

Scenario: High-income earner in California

• Income: $500,000/year
• Marginal tax bracket: 32% federal ordinary income
• State income tax bracket: 13.3% (California top rate)
• Investment portfolio: $2 million, cost basis $1 million (50% gain)
• Planning to sell: $200,000 from portfolio to fund a down payment
• Capital gain on the sale: $100,000

Your taxes on this sale:

Tax	Rate	Amount
Federal long-term capital gains	20%	$20,000
Net Investment Income Tax	3.8%	$3,800
State capital gains tax (California ordinary income rate)	13.3%	$13,300
Total Tax	37.1%	$37,100

That $100,000 gain costs you $37,100 in taxes. To cover a $200,000 down payment, you've sold $200,000 of investments, triggered $100,000 in gains (because your cost basis is 50%), and paid $37,100 in taxes.

Your real down payment cost: $237,100.

Compare that to someone in Texas with the same situation:

Tax	Rate	Amount
Federal long-term capital gains	20%	$20,000
Net Investment Income Tax	3.8%	$3,800
State income tax	0%	$0
Total Tax	23.8%	$23,800

Same $100,000 gain, but only $23,800 in taxes. Your down payment cost: $223,800.

That's a $13,300 difference just because of state residency. On a larger transaction (say, $500,000 in liquidation = $250,000 in gains), the difference could be $32,500 between California and Texas. For a person spending $500,000 on a down payment, that's a 6.5% cost difference based purely on geography.

The Variable That Most People Overlook: Your Cost Basis

Your actual tax bill depends heavily on your cost basis—the percentage of your portfolio that's unrealized gains versus cash.

If you built a $2 million portfolio over twenty years, your cost basis might be only 30%, meaning 70% of your portfolio is unrealized gains. That's a high-gain portfolio.

If you built a $2 million portfolio through regular contributions and you've reinvested all dividends, your cost basis might be 80%, meaning only 20% is unrealized gains. That's a lower-gain portfolio.

When you liquidate $200,000 from a 30% cost basis portfolio, you're realizing $140,000 in gains. When you liquidate $200,000 from an 80% cost basis portfolio, you're realizing only $40,000 in gains.

At a 37% combined tax rate, the difference in taxes is:

• 30% cost basis: $140,000 gain × 37% = $51,800 in taxes
• 80% cost basis: $40,000 gain × 37% = $14,800 in taxes

That's a $37,000 difference, just because of how you built your portfolio.

If you don't know your cost basis, this is worth finding out. Check your tax documents from prior year-end statements, or ask your broker. It dramatically affects how expensive liquidation will be.

Timing Matters: When You Realize the Gains

If you have control over when you liquidate, timing matters because capital gains are taxed in the year you realize them.

If you're in a year with unusually high income (maybe a bonus, a business sale, or exercised stock options), liquidating investments that year puts you in a higher tax bracket and might trigger NIIT thresholds you otherwise wouldn't hit.

If you can shift the liquidation to a different year with lower income, you might save taxes. This isn't always possible with home purchases (you need the money when you're closing), but it's worth considering if you have flexibility.

One strategy some high-income earners use: liquidate investments in a year when you expect lower income, or when you have major deductions coming (like large charitable gifts). The details are worth discussing with a tax advisor.

Special Cases and Planning Opportunities

The Stepped-Up Basis Opportunity

If you inherit investments, you get a "stepped-up basis" equal to the market value at the time of inheritance. That means if your parent bought a stock for $10,000 and it appreciated to $100,000, and then they pass away and you inherit it, your cost basis is $100,000 (the stepped-up value), not $10,000.

This is a powerful tax planning tool, but it's not one you can easily use for a near-term down payment.

Installment Sales and Deferred Payments

Some high-net-worth individuals use installment sales to spread capital gains across multiple years, thereby spreading the tax bill across multiple tax years. This is complex and requires careful structuring, but it's worth exploring if you're selling a large position.

Direct Charitable Giving

If you're charitably inclined, donating appreciated securities directly to charity (rather than selling them and donating cash) lets you avoid capital gains tax while getting a charitable deduction. This works for large gifts, but probably not for a home down payment.

Community Property and Marital Considerations

If you're married and live in a community property state (like California, Texas, or Washington), both spouses' investments might qualify for a stepped-up basis when one spouse passes away. This is a longer-term planning consideration, not relevant to an immediate home purchase, but worth knowing about.

How This Changes the Comparison Between Your Options

Now that you understand capital gains tax, you can see why it becomes such a huge variable when you're comparing down payment strategies.

Option 1: Cash down payment

• You liquidate investments, realize capital gains, and pay the capital gains tax.
• You've used that capital, so it's not invested anymore.
• Combined cost: down payment amount + capital gains tax + opportunity cost.

Option 2: Traditional mortgage with a smaller down payment

• You liquidate fewer investments (or none), so you pay less (or no) capital gains tax.
• But you carry a larger mortgage and pay mortgage interest instead.
• The mortgage interest, while high in absolute terms, might be lower than the capital gains tax you avoided.

Option 3: SBLOC

• You don't liquidate any investments, so you pay zero capital gains tax.
• You borrow against your portfolio instead.
• You pay interest on the borrowed amount, but you avoid the capital gains tax entirely and keep your portfolio invested.

For many high-net-worth investors, especially those in high-tax states with large unrealized gains, the SBLOC option becomes attractive precisely because of capital gains taxes. The interest cost of an SBLOC might be lower than the capital gains tax you'd owe by liquidating.

When Capital Gains Tax Actually Becomes a Non-Issue

There are situations where capital gains tax matters less:

Low cost basis portfolios: If you inherited your wealth or received a large gift, and you have a high cost basis (little unrealized gain), capital gains tax is minimal.

Low-tax states: If you live in Texas, Florida, or another no-income-tax state, your combined rate is lower, making liquidation more feasible.

Small portfolio relative to down payment: If you need $200,000 down but you have $500,000 in investments, the percentage of gains matters less.

Small unrealized gains: If most of your portfolio is recent contributions (not decades of gains), your cost basis is high and gains are minimal.

In these situations, a traditional mortgage or even a cash purchase might be more efficient than an SBLOC.

What You Actually Need to Know

If you're sitting on substantial investments and planning a home purchase, here's what you need to do:

1. Calculate your actual capital gains tax. Find your cost basis for the investments you might liquidate. Calculate the gain (sale price minus cost basis). Apply your federal rate (20% plus 3.8% NIIT if you're high-income), your state rate, and any other applicable taxes. Know the exact number.

2. Understand this is part of your total cost. Capital gains tax is often the largest hidden cost in a down payment. Account for it explicitly in your decision.

3. Compare all three options. Once you know your capital gains tax, you can compare: (a) the cost of liquidating to pay cash, (b) the cost of taking a mortgage, and (c) the cost of an SBLOC. These comparisons need to include the capital gains tax from liquidation.

4. Model your specific numbers. Because capital gains tax, opportunity cost, and interest rates are so variable, generic advice doesn't work. You need to model your specific situation: your portfolio, your cost basis, your tax bracket, current interest rates, and your expected investment returns.

Use a Tool Built for Your Situation

If you're a high-net-worth investor, you can't afford to make a $300,000–$500,000 down payment decision without understanding the role of capital gains tax. Standard mortgage calculators don't even mention it. They certainly don't account for opportunity cost or alternative strategies like SBLOCs.

Stockstead is a free calculator built specifically for investors who own substantial portfolios. It accounts for your actual capital gains tax, your state, your tax bracket, and your cost basis. It models all three options—cash, mortgage, and SBLOC—so you can see which costs the least for your situation.

A few minutes with the right calculator can save you tens of thousands in taxes.

Calculate Your Capital Gains Tax Impact →

For the decision-framing version of this analysis (the opportunity-cost framing rather than the tax mechanics), see The $200K Mistake: Liquidating Stock for a Down Payment.

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Tax rates current as of 2026. Long-term capital gains brackets reflect IRS Rev. Proc. 2025-32 (released October 2025) inflation adjustments. NIIT thresholds are statutory and unchanged since 2013. State rates referenced (California, New York, Texas) are current as of January 2026; verify with your state's revenue department before relying on these figures. This is not financial or tax advice. Tyler Singletary is the founder of Stockstead and is not a licensed financial advisor or CPA. Tax rules are complex and your specific situation matters — consult a licensed professional before making any liquidation decisions.