How Treasury bill auctions work (and how to read the results)

By StateYield · Published Oct 21, 2026 · Updated Oct 21, 2026

The Treasury sells bills at auction every week. If you buy at auction, whether through TreasuryDirect or a broker, the auction result sets your rate. Here's how the process works and how to read a results page, using a recent 13-week auction as the example.

What's sold, and when

Per TreasuryDirect, bills come in 4-, 6-, 8-, 13-, 17-, 26- and 52-week terms. The 52-week bill is auctioned every four weeks and the others weekly. Cash management bills are also sold "at various times and for variable terms," with no regular schedule. Each auction is announced a few days ahead with the offering amount and the deadlines.

Our records from Treasury's Fiscal Data auctions dataset (Jan 2, 2024 to Oct 20, 2026, excluding cash management bills) show the regular rhythm:

For 13-week bills, the most common closing times listed were 11:00 AM for non-competitive bids and 11:30 AM for competitive bids (Eastern time). Holidays shift the calendar, so check Treasury's announcement for a specific week. 147 of the 147 13-week auctions in our records were reopenings, meaning Treasury sold more of an existing bill that matures on the same day: 110 of a bill first issued as a 26-week bill and 37 of a bill first issued as a 52-week bill.

How bids are filled

There are two kinds of bids (TreasuryDirect). A non-competitive bid agrees to accept whatever rate the auction sets, up to $10 million per auction; that's the only kind you can place in TreasuryDirect. A competitive bid names the rate you'll accept, can be up to 35% of the offering, and has to go through a bank, broker or dealer.

Treasury first accepts all qualifying non-competitive bids. It then accepts competitive bids "from lowest to highest" rate until the offering is filled, and "all successful bidders get the same rate, yield, or discount margin as the highest accepted bid." That's a single-price auction: a small non-competitive buyer gets exactly the same rate as a bank. Under 31 CFR § 356.20, when there are more bids at the highest accepted rate than securities left, Treasury prorates those bids.

Reading the results

• High discount rate. The rate at which the auction cleared, quoted on a bank-discount basis using a 360-day year. It sets the price: price = 100 × (1 − rate × days ÷ 360) (TreasuryDirect; 31 CFR 356, App. B).
• Investment rate. The coupon-equivalent yield, based on the price you actually pay and a 365-day year (366 if a leap day falls within a year of issue). For bills of up to six months it's (100 − price) ÷ price × 365 ÷ days. Because it's comparable to other yields, it's the number we rank.
• Median and low rates. These show how spread out the accepted competitive bids were. Everyone still gets the high rate.
• Allotted at high. The percentage of bids placed exactly at the high rate that were filled, the proration described above.
• Bid-to-cover. How much was bid relative to how much was sold. In Treasury's data, the published ratio matches total bids divided by total accepted, after leaving out the Federal Reserve's own (SOMA) bids; we checked this against the published totals. A higher ratio means more demand. It describes that auction, but it doesn't change the rate you received.

Worked example: the Oct 13, 2026 13-week auction

You can check the published figures yourself:

• Price from the discount rate: 100 × (1 − 0.04085 × 91 ÷ 360) = 98.967403, matching the published price.
• Investment rate from the price: (100 − 98.967403) ÷ 98.967403 × 365 ÷ 91 = 4.185%, matching the published 4.185%.
• Bid-to-cover: ($260.2 billion − $5.4 billion) ÷ ($100.4 billion − $5.4 billion) = 2.68.

In dollars, a $10,000 bill from this auction cost about $9,896.74 and paid $10,000 at maturity, about $103.26 of interest over 91 days. That interest is federally taxable and exempt from state and local income tax; see Are T-bills taxed by states?

Where to find results

TreasuryDirect posts results after each auction. If you bid in TreasuryDirect, you can see your own result after 5 PM Eastern on auction day. Treasury's Fiscal Data API publishes the full records; when it hasn't posted a just-finished auction yet, we use TreasuryDirect's own results feed. This week's auctions are on our home page, and the 13-week rate history charts every 13-week auction since January 2024. Over that period the investment rate ranged from 3.622% (Jan 5, 2026) to 5.404% (Jan 2, 2024).

Live figures as of Oct 21, 2026, 5:25 PM CT; each yield carries its own source date. Latest 13-week auction (Oct 19, 2026): 4.195% high investment rate, source: TreasuryDirect auction results API (Fiscal Data not yet updated).

Sources

1. TreasuryDirect: Treasury Bills
2. TreasuryDirect: How Auctions Work
3. TreasuryDirect: Understanding Pricing and Interest Rates
4. 31 CFR Part 356, Appendix B: Formulas and Tables (eCFR)
5. 31 CFR § 356.20: How does the Treasury determine auction awards? (eCFR)
6. Treasury Fiscal Data: Treasury Securities Auctions Data