Treasury Floating Rate Notes (FRNs) are two-year marketable debt securities issued by the U.S. government whose interest payouts adjust automatically as short-term interest rates move. Unlike traditional fixed-rate Treasuries that lock in a single coupon for their entire lifespan, an FRN’s interest rate resets every week based on the prevailing yield of newly auctioned 13-week Treasury bills.
For investors navigating unpredictable interest rate environments, FRNs provide a direct mechanism to earn floating sovereign income while virtually eliminating the capital losses associated with bond duration. Readers seeking an overview of basic fixed-income structures can also consult our getting started guide for a broader foundation.
The Core Concept: Index Rate and Spread
Introduced by the U.S. Department of the Treasury in 2014, Floating Rate Notes represent the newest marketable debt category alongside bills, notes, bonds, and TIPS. According to official guidelines from TreasuryDirect, the interest rate of an FRN is calculated as the sum of two distinct components:
- The Index Rate: This component is tied directly to the highest accepted discount rate established at the weekly auction of 13-week (three-month) Treasury bills. Because the Treasury conducts 13-week bill auctions every week, the FRN index rate resets every week.
- The Spread: The spread is an adjustment rate determined at the initial public auction when the FRN is first issued. This spread remains fixed for the entire two-year life of the security.
Every business day, the Treasury applies the combined rate (Index Rate + Spread) to the note’s par value. The note accumulates interest daily, and the total accrued interest is distributed to investors every three months (quarterly).
A Sourced Comparison: FRNs vs. T-Bills and 2-Year Notes
To understand where Floating Rate Notes fit in the capital markets, it helps to compare them with alternative short-term government debt obligations, including traditional marketable Treasury securities and Treasury bill discount structures.
| Security Feature | 13-Week Treasury Bill | 2-Year Treasury FRN | 2-Year Fixed-Rate Note |
|---|---|---|---|
| Stated Maturity | 13 weeks (91 days) | 2 years | 2 years |
| Coupon Structure | Zero-coupon (issued at discount) | Floating (Index Rate + Spread) | Fixed semi-annual coupon |
| Reset Frequency | None (fixed yield to maturity) | Weekly (after 13-week bill auction) | None (coupon never changes) |
| Payout Timing | At maturity (face value) | Quarterly (every 3 months) | Semi-annually (every 6 months) |
| Duration Risk | ~0.25 years | ~1 week (near zero) | ~1.9 years |
| State & Local Taxes | Exempt | Exempt | Exempt |
Visualizing the FRN Coupon Mechanism
The diagram below highlights how the weekly 13-week bill auction output combines with the immutable auction spread to determine the daily interest accrual across a quarterly payment cycle.
Step-by-Step Worked Example (Hypothetical Calculation)
To see how an FRN payout accumulates in practice, consider an illustrative hypothetical scenario involving an investor holding ,000 in par value of a newly issued 2-year FRN.
Note: The interest rates, spreads, and dates in this section are strictly illustrative and hypothetical examples designed to demonstrate the statutory formula.
- Hypothetical Par Value: ,000.00
- Hypothetical Initial Auction Spread: +0.120% (12 basis points), fixed for 2 years.
- Hypothetical Week 1 Index Rate: 4.000% (based on the Monday 13-week T-bill auction).
- Hypothetical Combined Annualized Rate for Week 1: 4.000% + 0.120% = 4.120%.
The Treasury calculates daily accrued interest based on the actual number of days divided by 360 (the conventional money-market day-count basis for Treasury bills):
Daily Interest Formula:
Daily Interest = Par Value × (Annual Index Rate + Spread) / 360
Using our hypothetical numbers for the first 7-day period:
Daily Interest = ,000 × 0.04120 / 360 = .1444 per day Week 1 Total Accrual (7 days) = 7 × .1444 = .01
If the 13-week T-bill discount rate rises to a hypothetical 4.250% in Week 2, the new combined rate instantly adjusts to 4.370% (4.250% + 0.120%), raising the daily accrual to .2139 (.50 for the week). Across the full 13-week quarter, all daily interest amounts sum together into the quarterly cash coupon deposited into the investor’s brokerage or TreasuryDirect account.
Common Mistakes and Misconceptions
While Treasury Floating Rate Notes are straightforward in design, investors frequently make three common errors when analyzing them:
- Confusing the Index Rate with the Investment Yield: The index rate of an FRN is tied to the 13-week T-bill discount rate, not its investment (coupon-equivalent) yield. Because discount rates are calculated using a 360-day year and face value rather than purchase price, the quoted index rate is slightly lower than the annualized compound return.
- Expecting Significant Capital Gains During Rate Cuts: Traditional fixed-rate Treasury notes rise in price when market interest rates decline because their higher coupons become more valuable. Because an FRN’s coupon adjusts downward every week to reflect lower rates, its market price remains anchored near par (), offering virtually no duration-driven price appreciation.
- Assuming Zero Reinvestment Risk: While FRNs shield investors from capital losses when yields rise, they expose investors to reinvestment risk when yields fall. If the Federal Reserve eases monetary policy, the weekly coupon rate will drop in tandem with 13-week bill yields.
Related Fixed-Income Concepts
To deepen your understanding of government debt plumbing, explore these complementary market mechanisms:
- Duration and Convexity: Understand how fixed-coupon bonds experience price volatility when benchmark yields fluctuate, in contrast to floating-rate notes.
- T-Bill Discount Math: Learn how the Treasury calculates auction pricing on bills using discount formulas rather than semi-annual coupons.
- The Treasury Yield Curve: Explore how short-term bill rates diverge from long-term 10-year and 30-year bond yields during economic shifts.
Sources
- U.S. Department of the Treasury (TreasuryDirect) — Floating Rate Notes (FRNs)
- Federal Reserve Bank of St. Louis (FRED) — 3-Month Treasury Bill Secondary Market Rate, Discount Basis [TB3MS]
Disclosure: This article is for informational purposes only and is not investment advice.