Best T-Bill Duration in 2026 — Which Should You Choose?

Last updated: April 2026  ·  7 min read  ·  US investors

T-Bills come in six durations — from 4 weeks to 52 weeks. There is no single "best" one. The right choice depends on three things: when you need your money back, which way interest rates are heading, and how often you want to deal with reinvesting.

This guide breaks each duration down in plain terms — with real return comparisons and a clear recommendation for your situation.

Quick Answer — Best Duration by Situation

All T-Bill Durations — Full Comparison

Real Return Comparison — $10,000 at 4.5% Discount Rate

To show the actual dollar difference between durations, here is what $10,000 earns at each duration at a 4.5% discount rate (illustrative — check current auction rates before investing).

4-Week T-Bill — Maximum Flexibility

The 4-week T-Bill matures in 28 days — you get your money back roughly once a month. It is auctioned every Tuesday and is the most liquid T-Bill option. If rates are rising, this is your best friend — you reinvest every 4 weeks and capture each rate increase automatically.

Best for:

• Money you may need back within a month
• Investors who want to capture rising rates quickly
• Testing T-Bills for the first time with a short commitment
• Businesses parking payroll or operational cash temporarily

Downside:

• Requires the most active management — you reinvest every 4 weeks
• Yield is slightly lower than longer durations in normal rate conditions

8-Week T-Bill — Short-Term Cash Parking

The 8-week T-Bill is the middle ground between 4-week and 13-week. You get your money back in about 2 months, with a marginally better yield than the 4-week. It is auctioned every Tuesday alongside the 4-week bill.

Best for:

• Cash with a known 2-month horizon (e.g. quarterly tax payments)
• Investors who want slightly more yield than a 4-week without committing to 13 weeks
• Adding a second rung to a 4-week rolling ladder

Downside:

• Less commonly discussed than 4-week or 13-week — fewer resources available
• Yield advantage over 4-week is typically very small

17-Week T-Bill — Flexible Mid-Term Option

The 17-week T-Bill matures in about 4 months — it fills the gap between quarterly (13-week) and semi-annual (26-week). Auctioned every Wednesday, it is useful when you need more than 3 months but do not want to commit for 6.

Best for:

• Bridging a gap between quarterly and semi-annual cash needs
• Investors building a ladder who need a rung between 13-week and 26-week
• Fine-tuning a stagger in a multi-duration ladder

Downside:

• Less popular than 13-week and 26-week — less secondary market liquidity
• Auctioned weekly on Wednesdays — a different day than 13-week and 26-week (Monday)

13-Week T-Bill — Best for Beginners

The 13-week T-Bill matures every 3 months and is widely considered the best starting point for first-time investors. It is short enough to not feel intimidating, and you can reassess every quarter whether to keep rolling or switch to a longer duration.

Best for:

• First-time T-Bill investors — short enough to feel comfortable
• Investors who review their cash quarterly
• People in rising rate environments who want to reinvest every 3 months
• Aligning with quarterly tax planning or estimated tax payments

Downside:

• Yield slightly below 26-week and 52-week in normal conditions
• Requires reinvestment every quarter if rolling over

26-Week T-Bill — Most Popular Choice

The 26-week T-Bill is the most popular T-Bill for a reason — it hits the sweet spot. You lock in for 6 months, earn a competitive rate, and only need to think about it twice a year. If you are not sure which duration to pick, this is the safe default.

Best for:

• Investors who don't need money for 6 months
• Emergency fund portion that earns better than a savings account
• Semi-annual cash flow planning
• Investors who want good yield without committing a full year

Downside:

• Money locked for 6 months on TreasuryDirect (can sell on secondary market via broker)
• In rising rate environments, you miss higher rates for 6 months

52-Week T-Bill — Maximum Yield

The 52-week T-Bill locks your money in for a full year and pays the highest yield in normal conditions. It is the right choice when rates are falling — you lock in today's higher rate before it drops. Auctioned every four weeks.

Best for:

• Investors who definitely won't need the money for a year
• Locking in high rates when the Fed is expected to cut rates
• Maximizing yield on a known future expense (e.g. tax bill in 12 months)

Downside:

• Money is locked for a full year on TreasuryDirect
• In rising rate environments, you're stuck at a lower rate
• In an inverted yield curve, shorter T-Bills may actually yield more

Rising vs Falling Rates — Which Duration Wins?

This is the most important factor — more important than yield differences between durations. Getting rate direction right can add hundreds of dollars on a $10,000 investment over a year.

What is an Inverted Yield Curve — and Why Does It Matter for T-Bills?

Normally, the longer you wait, the more you earn. A 52-week T-Bill yields more than a 4-week one. That is a normal yield curve.

An inverted yield curve flips this. Short-term T-Bills pay more than long-term ones. This actually happened in 2022–2023 — 4-week T-Bills were briefly paying more than 52-week ones. If you assumed "longer = more yield," you would have picked the wrong one.

Rolling Over (Reinvesting) vs Locking In — Which is Better?

Rolling over means when your T-Bill matures you immediately buy another one — staying short and flexible. Locking in means buying a longer duration and waiting it out. Neither is always right — it depends on rates.

Best Strategy — The T-Bill Ladder

Not sure which duration to pick? A T-Bill ladder is the answer. Instead of putting all your money in one duration, you split it across several — so one always matures soon while the rest keeps earning. It is the most practical strategy for most people.

How a 6-rung ladder works with $60,000 (one rung per T-Bill duration):

As each T-Bill matures, you can reinvest into a new T-Bill of your chosen target duration. One common approach is to reinvest all tranches into 52-week T-Bills — within a year, all four rungs are 52-week bills maturing every quarter, giving you regular liquidity at the highest yield. Or use the Ladder Strategy Calculator to pick any target duration.

New to T-Bills? Read the full foundation guide first: What Are Treasury Bills — Complete Guide
Deciding if T-Bills are right for you? Are T-Bills Worth It? Honest Analysis

Frequently Asked Questions (FAQ)

Which T-Bill duration gives the highest return?

The 52-week T-Bill usually gives the highest return in normal conditions. During an inverted yield curve, shorter durations like 4-week or 13-week can yield more.

Which T-Bill duration is best for beginners?

The 13-week T-Bill is best for beginners. It offers a balance of yield and flexibility and matures every 3 months.

Should I choose a longer or shorter T-Bill when rates are falling?

You should choose longer T-Bills when rates are falling. A 52-week T-Bill locks in the current higher rate for a full year.

What is the most popular T-Bill duration?

The 26-week T-Bill is the most popular duration. It balances yield and flexibility with a manageable 6-month commitment.

Can I change my T-Bill duration after buying?

No, you cannot change a T-Bill after buying it on TreasuryDirect. If purchased through a brokerage, you can sell it on the secondary market at market price.

Is a T-Bill ladder better than picking one duration?

Yes, a T-Bill ladder is better for most investors. It provides regular cash access while maintaining steady returns across different durations.

What is the best T-Bill duration right now?

The best T-Bill duration depends on interest rates. Short-term T-Bills are better when rates are rising, while long-term T-Bills are better when rates are falling.