Guide

TIPS explained: Treasury Inflation-Protected Securities

Most bonds pay a fixed dollar coupon and return principal at maturity — but inflation quietly erodes what those dollars buy. Treasury Inflation-Protected Securities (TIPS) are U.S. government bonds designed to solve that problem: the principal adjusts with the Consumer Price Index (CPI), and semiannual interest is paid on the inflated balance. Investors quote TIPS in real yield — return above inflation — rather than nominal yield. That makes them the cleanest direct hedge against unexpected CPI spikes inside a fixed-income sleeve, but they are not a free lunch: negative real yields have appeared, phantom income creates federal tax headaches in taxable accounts, and TIPS still carry interest-rate risk like any long bond. This guide explains how CPI adjustments work, breakeven inflation math, where to buy TIPS (TreasuryDirect vs ETFs), how they compare to T-bills and I Bonds, tax traps, and where TIPS belong in a diversified portfolio.

How TIPS principal and coupons adjust

TIPS were first issued in 1997. The U.S. Treasury sells them in maturities of 5, 10, and 30 years through periodic auctions, with some older issues still trading in the secondary market. Each bond has a fixed coupon rate set at auction — but that rate applies to a principal that changes every six months.

The inflation adjustment uses the non-seasonally adjusted CPI-U (Consumer Price Index for All Urban Consumers). Twice a year, on each interest payment date, the Treasury multiplies the original face value by the ratio of the latest CPI reference index to the index at issuance. If CPI rises 3% over six months, a $1,000 TIPS might show an adjusted principal of roughly $1,030 before the next coupon calculation.

Interest payments follow the same rhythm as nominal Treasuries — twice annually — but the dollar amount equals coupon rate × adjusted principal / 2. At maturity, you receive the greater of adjusted principal or original face value. Deflation cannot erode principal below par at redemption, though interim adjusted principal can dip temporarily during deflationary stretches (coupon income falls accordingly until CPI recovers).

Lag matters: TIPS use CPI figures with a three-month lag relative to the payment date. A sudden inflation spike in April may not fully flow into your August payment. For long-term holders the lag averages out; for tactical traders it can create short-term tracking error versus spot inflation expectations.

Real yield vs nominal yield

When financial media quotes a 10-year Treasury at 4.2%, that is a nominal yield — it does not promise 4.2% purchasing power if inflation runs hotter. TIPS auction results instead report a real yield: the return you earn after CPI adjustments. A TIPS real yield of 1.8% means you expect roughly 1.8% annual return above realized inflation over the holding period, before taxes and fund expenses.

The relationship between nominal and real yields embeds the market’s inflation forecast. Economists call the gap the breakeven inflation rate:

Breakeven inflation ≈ Nominal Treasury yield − TIPS real yield (for the same maturity).

Example: if a 10-year nominal Treasury yields 4.3% and a 10-year TIPS real yield is 1.9%, breakeven inflation is about 2.4%. You “win” with TIPS versus holding the nominal bond if realized CPI averages above 2.4% over the decade; you lose if inflation undershoots. Breakeven rates move daily with supply, demand, and Fed expectations — they are not a forecast gospel, but they price the inflation insurance embedded in TIPS.

During periods of heavy central-bank bond buying or flight-to-safety demand, TIPS real yields can go negative. Buying a TIPS at −0.5% real yield locks in a guaranteed loss of purchasing power relative to CPI — you are paying a premium for certainty. Many retirees still hold TIPS in those environments because the alternative (nominal bonds) may embed even worse real outcomes if inflation surprises to the upside.

Where to buy TIPS

TreasuryDirect and auctions

Individual investors can participate in TIPS auctions at TreasuryDirect.gov — the same platform used for T-bill purchases. Auctions are typically non-competitive for retail (you accept the market clearing yield) or competitive for institutions bidding specific yields. Minimum purchase is $100 in face-value increments. Holding individual TIPS to maturity eliminates fund expense ratios and guarantees the CPI adjustment path for that specific CUSIP.

Secondary market and ETFs

Already-issued TIPS trade on the secondary market through brokers. Prices embed accrued inflation adjustments and market real-yield moves — buying between auctions is fine but requires checking clean vs dirty price (accrued inflation compensation).

Mutual funds and ETFs dominate retail TIPS exposure because laddering many individual CUSIPs is cumbersome. Popular ETFs include SCHP (broad TIPS), VTIP (short-duration TIPS), and STIP (ultra-short). Funds distribute monthly dividends that mix coupon income and principal adjustments; NAV fluctuates with real yields. Expense ratios are low (often 0.03–0.05%) but not zero — compare fund yield to individual bond real yield after fees.

TIPS vs I Bonds vs nominal Treasuries

Investors often conflate inflation-linked products. The differences matter:

TIPS — market-traded, principal adjusts with CPI, real yield set at auction, liquid in brokerage accounts and ETFs, subject to price volatility before maturity.
Series I Savings Bonds (I Bonds) — non-marketable, purchase limits ($10,000 per person per year at TreasuryDirect, plus $5,000 from tax refunds), fixed rate plus inflation component, cannot be sold on secondary market, early redemption penalties within five years. Better for small, long-hold savers; worse for large portfolios needing liquidity.
Nominal Treasuries and T-bills — no CPI adjustment; win when inflation undershoots breakeven; simpler tax treatment on T-bills (discount accretion taxed at maturity for originals). T-bills suit cash sleeves; nominal notes suit predictable nominal income needs.

A common strategy: hold I Bonds up to annual limits for tax-deferred inflation protection, fill additional inflation hedge with TIPS funds in brokerage IRAs or 401(k)s, and use T-bills for near-term cash. See our broader inflation markets guide for how CPI releases move breakevens and Fed policy.

Tax treatment and the phantom income problem

TIPS interest and inflation adjustments are taxable at the federal level in the year they occur, even though you do not receive the principal uplift as cash until maturity or sale. This phantom income surprises first-time buyers: CPI rises 5%, your 1099-OID shows additional taxable income, but your brokerage account balance may not have grown by that amount if you hold individual bonds.

TIPS are exempt from state and local income tax — like other U.S. Treasuries — but not from federal tax. Holding TIPS inside a traditional or Roth IRA defers or eliminates the phantom-income issue. In taxable accounts, some investors prefer TIPS ETFs (which distribute income regularly, aligning cash with taxes somewhat) or allocate inflation hedge to tax-advantaged buckets instead.

Selling TIPS before maturity triggers capital gains or losses on price moves separate from OID income. After long bull markets in TIPS (falling real yields), secondary-market prices can trade at premiums above adjusted principal — creating capital loss potential if real yields rise sharply.

Duration, rate risk, and the yield curve

TIPS are not cash equivalents. A 30-year TIPS fund has substantial interest-rate sensitivity: when real yields rise, prices fall even if CPI is stable. Short-duration funds (VTIP, STIP) reduce that volatility for investors who want inflation protection without long bond swings.

The shape of the real yield curve — how much extra real return longer maturities pay — informs ladder design. When the yield curve is inverted in nominal space, real yields may also invert, making intermediate maturities attractive on a risk-adjusted basis. Laddering 5-, 10-, and 30-year TIPS auctions diversifies reinvestment timing across inflation and rate cycles.

When TIPS make sense — and when they do not

Good fits:

Retirees funding known real spending needs (healthcare, rent) over 10+ years.
Investors who believe realized inflation will exceed breakeven rates embedded in nominal bonds.
Tax-advantaged accounts where phantom income is not a drag.
Core bond portfolios seeking diversification versus corporate credit risk — TIPS are full-faith-and-credit U.S. government debt.

Poor fits:

Emergency cash or horizons under two years — use T-bills or money market funds instead.
Taxable accounts without cash to pay tax on phantom OID income during high-inflation years.
Investors betting on sustained deflation or below-breakeven CPI — nominal Treasuries would outperform.
Those who already hold heavy commodity or equity “inflation hedge” sleeves and would double-count risk without rebalancing.

Retail checklist

Check the current 10-year TIPS real yield and compare to historical averages — negative real yields require a deliberate reason to buy.
Calculate breakeven inflation versus nominal Treasuries of the same maturity.
Choose account placement — prefer IRAs/401(k)s for individual TIPS; taxable accounts suit ETFs if you accept distribution taxation.
Pick duration — short TIPS funds for stability, long funds for maximum inflation beta and rate risk.
Compare ETF expense ratios and tracking difference vs buying at TreasuryDirect auctions.
Reserve I Bond annual purchase limits before duplicating inflation exposure entirely in TIPS.
Plan for federal tax on OID in taxable accounts — set aside cash or hold in tax-deferred wrappers.
Rebalance after large CPI moves — TIPS allocations can drift above target when inflation spikes.
Revisit breakeven math when the Fed shifts policy — real yields can move faster than CPI.

Key takeaways

TIPS principal rises and falls with CPI-U — coupons pay on adjusted principal; face value is floored at par at maturity.
Real yield is the quoted return above inflation — compare to nominal Treasuries via breakeven inflation.
Phantom income taxes make account placement critical in taxable brokerage accounts.
TIPS still have duration risk — falling real yields boost prices; rising real yields hurt, independent of CPI.
ETFs and TreasuryDirect both work — funds for simplicity and size; individual bonds for hold-to-maturity precision.