Are I Bonds a Good Place for a Down Payment Fund?

Series I savings bonds got a lot of attention when inflation was high and their rates jumped. They're backed by the U.S. government, protect against inflation, and are easy to buy. But they come with rules that matter a great deal if you're saving for a home: a one-year lockup, an interest penalty for early redemption, and annual purchase limits.

This guide explains how I bonds work and when they do, and don't, make sense for a down payment.

How I bonds work

I bonds are savings bonds issued by the U.S. Treasury. According to TreasuryDirect, their interest rate combines two parts:

• A fixed rate, which stays the same for the life of the bond.
• An inflation rate, which is reset every six months based on changes in the Consumer Price Index.

New rates are announced each May and November. You can see current and past rates on TreasuryDirect's I bond rates page. Interest compounds semiannually and is added to the bond's value.

The rules that matter for home savers

One-year lockup

You can't cash an I bond for the first 12 months after you buy it. For a down payment, this is the biggest consideration: money you might need within a year shouldn't go into new I bonds.

Three-month interest penalty before five years

If you cash an I bond after one year but before five years, you lose the last three months of interest. After five years, there's no penalty.

Purchase limits

Electronic I bonds bought through TreasuryDirect are limited to $10,000 per person per calendar year. That limits how much of a larger house fund you can put in them.

Taxes

I bond interest is subject to federal income tax but exempt from state and local income taxes, similar to Treasury bills. You can generally defer federal tax until you cash the bond.

Comparing I bonds with other options

When I bonds can fit

• Your purchase is more than a year away, and you're comfortable not touching part of the fund for at least 12 months.
• You're worried about inflation eating into your savings over a multi-year horizon.
• The current composite rate is competitive with savings accounts, CDs and T-bills after taxes. That depends on the rate environment when you buy. For context, the effective federal funds rate averaged 3.88% in October 2026, which influences what savings accounts and T-bills pay.

When to skip them

• You might buy within a year. The lockup makes them unusable.
• You need most of your fund liquid for earnest money, closing costs and a fast closing.
• Rates elsewhere are clearly higher. I bonds aren't automatically the best deal; compare current rates.

The cost of the early-redemption penalty

Suppose you hold $10,000 of I bonds and cash them at the 18-month mark to buy a home. You'd give up three months of interest. At a hypothetical 4% composite rate, that's roughly $100. That's not huge, but it's worth knowing, and it's less than many CD penalties. The rate here is illustrative; actual rates change every six months.

How I bonds could fit into a house fund

A reasonable approach for someone two to three years from buying:

1. Keep near-term money liquid in a high-yield savings account: earnest money, a cushion and anything you might need within a year. See how to find a good HYSA.
2. Use CDs or T-bills for money with a known window. See our CD ladder and T-bill guides.
3. Consider I bonds for a slice you're confident you won't touch for at least a year, if the current rate is competitive.

On a 10% down payment target of $39,330 on the national median sales price of $393,300 (Q3 2026), the $10,000 annual limit means I bonds can only be one part of the plan for most buyers.

Common questions

Can I buy I bonds with my tax refund? You can use part of a federal tax refund to buy paper I bonds, subject to their own annual limit, in addition to the electronic limit. TreasuryDirect explains the current rules.

Can I bonds lose value? The bond's redemption value doesn't fall below what you paid. The composite rate has a floor of zero, so a six-month period with deflation can mean no interest for that period, but not a loss of principal.

Do I bonds count as assets for a mortgage? Lenders generally look at verified assets you can access. Bonds you can't redeem yet, because of the one-year lockup, may not be usable for closing funds. Ask your lender.

Extra reading on savings bonds

TreasuryDirect covers the mechanics. A beginner savings bonds or Treasury investing book can help with tax timing, redemption rules and how I bonds fit next to an HYSA or T-bill ladder.

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Practical takeaways

• I bonds pay a fixed rate plus an inflation rate that resets every six months.
• You can't cash them for 12 months, and you lose three months of interest if you cash them before five years.
• Electronic purchases are capped at $10,000 per person per calendar year.
• Interest is exempt from state and local tax.
• They can work for long-horizon slices of a house fund, not for money you'll need within a year.
• Track every account, including bonds, in our savings tracker, and see our comparison of where to keep a house fund.

Sources

• TreasuryDirect: I bonds
• TreasuryDirect: I bond interest rates
• TreasuryDirect: Treasury bills
• FDIC: Understanding deposit insurance

Rates in the example are illustrative and change every six months. This article is for education only and is not financial or tax advice.