I Bonds and Treasuries

US Treasury securities are the safest investment vehicle in the world. They are backed by the full faith and credit of the US government and have never defaulted in modern history. For an individual investor, they fill specific roles that other vehicles cannot: zero-default-risk savings, inflation protection, and predictable income.

This page is about the four main types — I bonds, T-bills, T-notes/T-bonds, and TIPS — what each does, where each fits, and how to actually buy them.

The four main types

Series I Savings Bonds (I bonds)

Inflation-protected savings bonds. The interest rate is the sum of two components, set every six months:

- **Fixed rate**: locked in when you buy; stays for the life of the bond

- **Inflation rate**: changes every six months based on CPI-U

Combined rate is the composite rate quoted at TreasuryDirect.

**Purchase limits**: $10,000/year electronic + $5,000/year paper (via tax refund) per Social Security number. Spouses each get their own limit.

**Holding period**: minimum 1 year; if redeemed before 5 years, you forfeit the most recent 3 months of interest.

**Tax treatment**: federal tax on interest (but deferrable until redemption); state and local tax-free.

**Maximum hold**: 30 years.

Treasury Bills (T-bills)

Short-term debt: 4-week, 8-week, 13-week, 26-week, or 52-week maturities.

Sold at a discount to face value; redeemed at face value at maturity. The difference is the yield.

**Purchase**: at TreasuryDirect or any brokerage.

**Tax treatment**: federal tax on interest; state and local tax-free.

**Use case**: short-duration, near-cash equivalent. Common for the "tier 2" portion of a larger emergency fund.

Treasury Notes (T-notes) and Treasury Bonds (T-bonds)

Longer-term debt: 2-year, 3-year, 5-year, 7-year, 10-year (notes); 20-year and 30-year (bonds).

Pay interest semi-annually; mature at face value.

**Use case**: bond allocation in a portfolio, alternative to corporate bonds when the small yield premium does not justify credit risk.

Treasury Inflation-Protected Securities (TIPS)

Similar to T-notes/bonds but with principal that adjusts with inflation (CPI-U).

- 5-year, 10-year, 30-year maturities

- Pay a fixed real rate of interest on the inflation-adjusted principal

- Total return = real interest + inflation adjustment

**Tax treatment**: the inflation adjustment is taxed as it accrues (the "phantom income" problem) — so TIPS work better in tax-deferred accounts than in taxable.

Where each fits

Emergency fund (deep tier)

I bonds and short T-bills are the right vehicles for the deep portion of a larger emergency fund — the part you do not need in the next 12 months.

I bonds: locked for 1 year, partial penalty until 5 years. Acceptable if you are not relying on the funds in year 1.

T-bill ladder: a 4/8/13/26/52-week ladder gives you continuous monthly maturities. As each rolls off, reinvest if not needed.

Inflation protection

I bonds are the cleanest inflation hedge available to retail investors. The 0% real return floor (you cannot lose principal in real terms) plus the variable inflation component gives you an asset that exactly tracks CPI in normal periods and beats it during deflation. The $10K annual limit makes it inadequate for large portfolios but useful as a corner.

TIPS provide similar protection at any scale, with daily liquidity and longer maturities. Best held in tax-deferred accounts due to phantom-income issues.

Bond allocation

For a household holding bonds as part of a balanced portfolio, Treasuries make sense as the core. The yield premium of corporate bonds is modest; the risk of credit events during stress is real. A TIPS / T-note mix in the bond allocation matches inflation while providing predictable nominal yield.

Specific safe-money goals

Down payment savings 12–24 months out: a T-bill ladder with rungs maturing on the planned use timeline gives you guaranteed yield and predictable cash availability.

I bonds in detail

I bonds have a specific set of mechanics worth understanding:

How the rate is calculated

The composite rate combines the fixed rate and the inflation rate per a formula. The composite rate applies to all I bonds regardless of when they were purchased; the fixed rate is locked at purchase.

A fixed rate of 1.0% on an I bond purchased today means the I bond will yield 1.0% above inflation for as long as you hold it. A fixed rate of 0% means it will exactly track inflation.

When the fixed rate matters

Buying I bonds when the fixed rate is high (1%+ historically) is significantly better than buying when it is 0%. The fixed rate is set every May and November.

If the fixed rate is 0% and you have an existing I bond with a higher fixed rate, hold the existing bond rather than buying new.

Liquidity

You cannot redeem an I bond in the first 12 months (period). After 12 months you can redeem at any time, with a 3-month interest penalty if redeemed before 5 years.

This makes I bonds genuinely good but slightly inflexible. Plan accordingly: do not put your front-line emergency fund in I bonds.

Annual purchase limit

$10,000 electronic + $5,000 paper per person. Married couples can buy $20K electronic + $10K paper combined. Each child can have their own bonds (in a custodial account).

For larger inflation-protection allocation, TIPS are the alternative.

Buying I bonds

I bonds are sold only at TreasuryDirect (treasurydirect.gov). The site interface is dated and occasionally frustrating, but the mechanics work:

1. Open a TreasuryDirect account (15 minutes)

2. Link a bank account

3. Purchase I bonds via "BuyDirect"

4. Select term and amount

Set up a Payroll Savings Plan if buying regularly; otherwise just buy manually.

T-bills in detail

T-bills are short-duration government debt — useful for cash management at scale.

How they work

Sold at a discount, redeemed at face value. A 13-week T-bill at 4% yield: you pay $99 today, receive $100 in 13 weeks. The difference is the yield.

Auctions vs. secondary market

T-bills are issued at weekly auctions. You can:

- Buy at auction (TreasuryDirect or brokerage)

- Buy on secondary market (brokerage) at slightly different prices

For most retail investors, brokerage purchase (Fidelity, Schwab, Vanguard) is simpler than TreasuryDirect for T-bills, and the spread is minimal.

Laddering

A T-bill ladder is a common cash-management strategy:

- Equal allocations to 4-week, 8-week, 13-week, 26-week, 52-week T-bills

- As each matures, reinvest in 52-week

- After ramping up, you have rolling weekly liquidity plus full-curve yield

For a $50K emergency fund tier 2, a T-bill ladder produces yields competitive with HYSAs while remaining state-tax-free.

Tax treatment

T-bills are state-tax-free. For high-state-tax residents (CA, NY, NJ, OR, etc.), this can produce a meaningful effective-yield advantage over corporate or municipal bonds.

TIPS in detail

TIPS provide inflation protection at scale and longer maturities than I bonds.

How they work

Principal adjusts with CPI-U. Interest is a fixed real rate paid semi-annually on the adjusted principal.

If you buy $10K of TIPS at issue and CPI rises 5% in the first year, the principal becomes $10,500. The interest payment in year 2 is the real rate × $10,500.

At maturity, you receive the inflation-adjusted principal (or the original principal if there has been deflation, whichever is greater).

The phantom income problem

The annual inflation adjustment is taxable income for the year it accrues, even though you do not receive cash for it. This makes TIPS less efficient in taxable accounts.

The standard solution: hold TIPS in tax-deferred accounts (401(k), traditional IRA). The phantom income is sheltered.

For taxable accounts: I bonds are usually preferred (they defer taxes until redemption), or TIPS funds (which distribute the gains, allowing taxes to flow naturally rather than as phantom income).

Buying TIPS

Available at TreasuryDirect, brokerages, and as ETFs (TIP, SCHP, VTIP, etc.).

For most investors: a TIPS ETF in a tax-deferred account is the simplest path. Direct TIPS at TreasuryDirect work for those who want individual securities.

Comparing the four

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A working portfolio integration

Sample allocation for a household with $50K of safe-money savings and inflation concerns:

- **Front-line emergency fund** ($15K): HYSA at 4%+ yield

- **Tier 2 emergency fund** ($15K): T-bill ladder (4/8/13/26/52-week rungs)

- **Inflation protection** ($10K/year): max I bonds via TreasuryDirect

- **Long-horizon safe money** ($10K): TIPS or TIPS ETF in tax-deferred account if applicable

This stack produces ~4–5% yield in 2026 conditions, full inflation protection on the corner allocation, and full liquidity on most of the balance.

Common failure patterns

- **Holding all "safe money" in checking at 0.01%.** Move to HYSA, T-bills, or I bonds.

- **Skipping I bonds because of the 1-year lock.** $10K/year not used is $10K of inflation protection foregone.

- **Holding TIPS in taxable accounts.** The phantom income is real and inefficient.

- **Buying long-dated Treasuries for "safety" without understanding interest-rate risk.** Long T-bonds drop substantially when rates rise.

- **Ignoring state-tax-free advantage.** For high-tax states, the difference between state-taxable and state-tax-free yields can be 1%+ in effective terms.