4-Week Treasury Bills Explained: A Complete Beginner Guide for 2026
4-Week Treasury Bills Explained: Why This Short Maturity Matters
A 4-week Treasury bill may look simple: you buy a short-term U.S. government security and receive its value at maturity. But the way you earn money is different from a savings account or a certificate of deposit. The bill is generally purchased at a price below its face value, and the difference represents the interest you earn.
That short 28-day maturity is the part worth paying attention to. It can make a 4-week T-bill useful for money that has a known near-term purpose, while also giving investors a chance to reinvest after maturity. If you’re new to Treasury securities, start with our
Treasury Bills Explained guide
before going deeper.
What You’ll Learn
How Do 4-Week Treasury Bills Work?
A 4-week Treasury bill is a short-term U.S. government security that matures in 28 days. Instead of paying a regular coupon, it is generally bought for less than its face value and redeemed at face value when it matures. The difference between the purchase price and the amount received at maturity represents the bill’s interest.
Key Takeaways
The standard 4-week bill matures after 28 days.
Your return generally comes from the difference between the purchase price and face value.
The short maturity can suit money with a near-term purpose.
Treasury interest is generally subject to federal income tax but exempt from state and local income taxes.
After maturity, you can use the proceeds or consider buying another bill.
A future 4-week bill may have a different yield, so today’s return should not be assumed for every rollover.
Bottom line:
A 4-week Treasury bill is built around a short 28-day maturity. The key is to look beyond the quoted rate and understand the purchase price, maturity value, taxes and what you plan to do with the money afterward.
4-Week Treasury Bills at a Glance
| Quick Fact | What It Means |
|---|---|
| 4-week term | The bill is scheduled to mature 28 days after its issue date. |
| No periodic coupon | You do not receive monthly or quarterly interest payments. |
| Maturity value | At maturity, the Treasury pays the bill’s face value under its terms. |
| Reinvestment | After maturity, you can use the proceeds or buy another Treasury security. |
QUICK TAKE:
The defining feature of a 4-week Treasury bill is its short 28-day maturity. Its return comes from the relationship between the purchase price and face value, rather than from a regular coupon payment. That makes the timing of your cash need just as important as the quoted yield.
4-Week Treasury Bills: A Complete Beginner Guide
If you have never bought a Treasury bill, the first thing to understand is that a 4-week Treasury bill is a short-term U.S. government debt security. The Treasury issues it with a fixed maturity of 28 days. You are not opening a bank account or depositing money with the government. You are buying a marketable Treasury security.
The way the return works is also different from a typical savings account. A 4-week T-bill is generally sold at a price below its face value. When it matures, the Treasury pays the face value. The gap between those amounts is the interest earned on the bill.
What Does “4-Week” Actually Mean?
The name refers to the bill’s term. A standard 4-week Treasury bill has a 28-day maturity. That short window can be useful when your goal is measured in weeks rather than years.
For example, someone setting aside money for a known expense about a month away may care more about the maturity date than about receiving periodic income. The bill is designed around that short timeline.
How the Money Moves
One detail beginners often miss:
the quoted T-bill discount rate is not the same thing as simply subtracting a percentage from the amount you invest. The purchase price, face value, term and quoted yield all work together to determine the actual return.
How 4-Week Treasury Bills Work
A 4-week Treasury bill starts with a U.S. Treasury auction. Investors can buy newly issued bills through TreasuryDirect or through a bank or brokerage that offers Treasury securities. The bill has a 28-day term, so the maturity date is known when the security is issued.
Unlike a Treasury bond, a 4-week T-bill does not make scheduled interest payments during the holding period. Treasury bills are generally issued at a discount to face value. At maturity, the bill is redeemed at its face value under its terms. The difference between the purchase price and face value is the gross interest earned.
The 4-Week T-Bill Process
Review the auction
Check the available 4-week bill, auction schedule and purchase details.
Place your order
Buy through TreasuryDirect or an eligible bank or brokerage account.
Hold for 28 days
The bill remains outstanding until its scheduled maturity date.
Receive the maturity value
At maturity, the Treasury pays the bill’s face value according to its terms.
Simple Example: Where the Interest Comes From
Imagine a 4-week Treasury bill with a $10,000 face value that you purchase for $9,950. If you hold the bill until maturity, you receive $10,000 according to its terms. The $50 difference represents the gross interest on that example.
Keep this in mind:
The $50 example is illustrative only. Actual purchase prices, discount rates and investment yields vary by auction and market conditions. The discount amount should not be confused with the quoted annualized yield.
Benefits and Drawbacks of 4-Week Treasury Bills
A 4-week Treasury bill can be useful for a specific type of cash: money you can leave untouched for a short period. But the short maturity also creates trade-offs. Here is what to consider before buying one.
- Very short maturity:
Your money is scheduled to reach maturity after 28 days. - U.S. government security:
A Treasury bill is a direct obligation of the U.S. government, rather than a bank deposit. - No periodic coupon:
You do not have to wait for monthly or quarterly interest payments. - Tax advantage at the state level:
Treasury interest is generally exempt from state and local income taxes, although federal income tax generally applies.
- No regular income stream:
The return is built into the purchase price rather than paid as a recurring coupon. - Reinvestment risk:
After 28 days, a new bill may offer a different yield. - Cash is committed until maturity:
If you need the money sooner, selling before maturity may expose you to a different market price. - Inflation can reduce real value:
Even when you earn interest, rising prices can reduce what that money can buy.
The key trade-off:
A 4-week T-bill gives you a short, defined maturity, but that also means you must decide what to do with the money again relatively soon. For a longer goal, repeatedly reinvesting may produce a different result as future Treasury yields change.
4-Week T-Bills vs Other Short-Term Options
A 4-week Treasury bill is only one way to hold money for a short period. A money market account, high-yield savings account, CD, or another Treasury bill can work differently. The right comparison depends on when you need the money, how much access you want, and how the return is structured.
| Option | Typical Structure | Access to Money | Insurance / Guarantee |
|---|---|---|---|
| 4-Week T-Bill | 28-day Treasury security; generally bought below face value | Primarily at maturity; can be sold earlier in the secondary market | Not FDIC-insured; direct U.S. government obligation |
| 8-Week T-Bill | Short-term Treasury security with an 8-week maturity | Primarily at maturity; earlier sale is possible through the market | Not FDIC-insured; direct U.S. government obligation |
| Money Market Account | Bank deposit account that generally earns interest | Generally easier access than a fixed-maturity security | FDIC insurance may apply at an eligible insured bank, subject to limits |
| High-Yield Savings Account | Bank deposit account with a variable interest rate | Generally designed for easier withdrawals | FDIC insurance may apply at an eligible insured bank, subject to limits |
| CD | Bank deposit held for a specified term, usually at a stated rate | Early withdrawal may involve account-specific restrictions or penalties | FDIC insurance may apply at an eligible insured bank, subject to limits |
When the Timeline Matters Most
If you have a known date for a future expense, the 28-day maturity of a 4-week T-bill gives you a defined schedule. A deposit account may offer easier access, while a longer Treasury bill or CD may extend the holding period.
One Detail to Watch
Treasury bills and deposit accounts quote returns differently. A T-bill’s annualized yield does not mean you earn that full percentage in 28 days. Compare the actual purchase price, maturity value, holding period, and access rules.
Research tip:
If you are comparing a Treasury bill with a money market account or CD, look beyond the headline rate. Your decision can change based on liquidity, maturity date, taxes, deposit insurance, and what you plan to do with the money afterward.
Costs, Taxes, Risks & Expert Tips for 4-Week T-Bills
A 4-week Treasury bill has a simple structure, but the details can affect your actual return. Look at the purchase price, maturity value, taxes, and what could happen if your plans change before the 28-day term ends.
Costs
TreasuryDirect charges no purchase fee or commission for buying marketable Treasury securities. You still pay the purchase price of the security. A brokerage may have its own pricing or charges.
Taxes
Treasury bill interest is subject to federal income tax but exempt from state and local income taxes. For a bill held to maturity, the difference between the purchase price and face value is generally treated as interest income.
Risks to Know
Reinvestment risk is important because the next 4-week bill may offer a different yield. Inflation can also reduce purchasing power. Selling before maturity exposes you to the current market price.
Expert Tips Before You Buy
- Check the maturity date before focusing on the quoted annualized yield.
- Compare the purchase price with the maturity value to see the dollar amount you could earn.
- If you may need the money early, understand that a sale before maturity occurs at the market price.
- Before reinvesting, compare the new yield rather than assuming it will match your previous bill.
Official sources:
TreasuryDirect
and
IRS Publication 550
provide additional information on Treasury purchases and tax treatment.
Common 4-Week T-Bill Mistakes and a Simple Real-Life Example
Most mistakes with 4-week Treasury bills are not complicated. They usually come from misunderstanding the quoted yield, maturity date, or what happens after the bill matures.
Mistake #1: Treating the Annualized Yield as 28-Day Interest
A quoted T-bill investment rate is annualized. You do not simply earn that percentage on your money in 28 days.
Mistake #2: Ignoring the Maturity Date
If the cash is needed for a bill, tuition payment, or other expense, check the actual maturity date rather than assuming the money will be available exactly four calendar weeks after purchase.
Mistake #3: Forgetting the Next Step
A maturing bill returns your money. If you want to keep the strategy going, you must decide whether to spend, hold, or reinvest the proceeds.
Real-Life Example: A $10,000 4-Week T-Bill
Suppose an investor buys a 4-week T-bill with a $10,000 face value for an illustrative purchase price of $9,950. If the investor holds it until maturity, the bill pays $10,000 according to its terms.
The $50 difference represents the gross interest in this simplified example. The investor should then consider federal taxes and decide what to do with the $10,000 proceeds.
Important:
The $9,950 purchase price and $50 return above are purely illustrative. Actual auction prices and investment rates change. The quoted annualized rate should not be confused with the dollar return over one 28-day holding period.
Who Should Choose 4-Week T-Bills?
A 4-week Treasury bill can make sense when you have money that does not need to be spent immediately but may be needed within a fairly short period. The key question is not simply how much risk you can tolerate. It is whether the 28-day maturity fits your cash-flow plans.
A 4-Week T-Bill May Fit If You:
- Have a known short-term cash timeline.
- Can leave the money invested until maturity.
- Want direct exposure to a short-term U.S. Treasury security.
- Are comfortable deciding what to do with the proceeds after 28 days.
Another Option May Fit Better If You:
- Need unrestricted access to the cash.
- Want a longer or more predictable investment period.
- Prefer keeping emergency money in a readily accessible deposit account.
- Do not want to manage repeated maturity and reinvestment decisions.
Bottom line:
A 4-week T-bill is primarily a short-term cash-management choice. Match the maturity date with your actual cash need, then compare the available yield, taxes, liquidity and reinvestment options.
8 Frequently Asked Questions About 4-Week Treasury Bills
1. What is a 4-week Treasury bill?
A 4-week Treasury bill is a short-term U.S. government debt security with a 28-day maturity. It is generally purchased below its face value and pays the face value at maturity.
2. How do 4-week T-bills make money?
The return generally comes from the difference between the purchase price and the bill’s face value at maturity. There is no regular monthly or quarterly coupon payment.
3. How much does a 4-week T-bill cost?
The purchase price depends on the auction result. Treasury bills are generally issued at a discount, so the amount paid can be less than the face value received at maturity.
4. Are 4-week Treasury bills taxable?
Yes. Treasury bill interest is subject to federal income tax but is exempt from state and local income taxes. For a typical bill held to maturity, the discount is generally reported as interest income.
5. Can I sell a 4-week T-bill before maturity?
Treasury bills are marketable securities, so they can generally be sold before maturity through a broker or other available secondary-market channel. The market price may be different from your purchase price.
6. Can I reinvest a 4-week T-bill after it matures?
Yes. You can use the maturity proceeds to purchase another Treasury security. The new bill will have its own auction price and yield, so the future return can differ from the previous bill.
7. Are 4-week T-bills FDIC insured?
No. A Treasury bill is not a bank deposit, so it is not covered by FDIC deposit insurance. It is a direct debt obligation of the U.S. government.
8. Is a 4-week T-bill right for emergency savings?
It depends on how quickly you may need the money. An emergency fund generally needs convenient access, while a 4-week T-bill has a defined maturity and can involve market-price risk if sold before maturity.
Quick reminder:
The quoted T-bill yield is annualized. It should not be interpreted as the amount you will earn over only 28 days.
Final Verdict: Are 4-Week Treasury Bills Worth Considering?
A 4-week Treasury bill is a simple short-term Treasury security with a defined 28-day maturity. It generally earns money through the difference between its purchase price and face value at maturity rather than through regular interest payments. Current Treasury offering documents identify the 4-week bill as a 28-day security.
The main question is what you need the money to do. If your cash can remain invested for the full term, the short maturity may fit a defined near-term cash plan. If you need frequent access, a deposit account may offer a different level of convenience.
The Bottom Line
Before buying, check the auction price, maturity date, federal tax treatment, liquidity needs and your reinvestment plan. A 4-week T-bill can be evaluated alongside savings accounts, money market accounts and CDs based on those factors—not simply by looking at the headline annualized yield.
Treasury bills are direct U.S. government obligations, while bank savings products are deposits with different access and insurance rules. Treasury interest is subject to federal income tax but exempt from state and local income taxes.
Related Resources & Authority Sources
If you want to keep researching short-term Treasury investments, these FinanceInvestment guides can help you compare Treasury bills with other options and understand how the pieces fit together.
Treasury Bills Explained: Complete Guide
How Do Treasury Bills Make Money?
Official Sources
TreasuryDirect — Marketable Securities
— official information on Treasury bills, notes and bonds.
TreasuryDirect — Understanding Pricing
— explains how Treasury bill pricing relates to face value.
IRS Publication 550 — Investment Income and Expenses
— covers federal taxation of Treasury bill interest.
Have a Money Question? Keep Exploring.
A 4-week Treasury bill is one part of short-term cash planning. If you are comparing Treasury bills with savings accounts, CDs, or money market options, keep researching the details that matter to your own timeline, access needs, taxes, and investment goals.
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