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. The one you choose affects your yield, how often you can reinvest, and when you get your money back. There is no single "best" duration — it depends entirely on your situation.

This guide breaks down every duration with real return comparisons, the right situation for each, and how the current rate environment affects your choice.

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 is the shortest available duration. It matures in 28 days and is auctioned every Tuesday, making it the most liquid T-Bill option.

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 (56-day) T-Bill is auctioned every Tuesday alongside the 4-week bill. It offers a slightly longer hold than the 4-week with a marginally better yield, making it useful for cash you won't need for about two months.

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 (119-day) T-Bill is auctioned every Wednesday. It sits between the 13-week and 26-week durations and is a useful option when you want more than a quarter but less than six months.

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 (91-day) T-Bill is auctioned every Monday and matures quarterly. It is widely considered the best starting point for first-time T-Bill investors.

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 (182-day) T-Bill is the most widely purchased duration by individual investors. It offers a strong balance of yield and flexibility — you lock in for 6 months, check in twice a year, and earn a competitive rate.

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 (364-day) T-Bill is the longest available T-Bill duration. In a normal yield curve environment, it offers the highest yield of any T-Bill. It is 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?

The current interest rate environment is the single most important factor in choosing your T-Bill duration. Getting this right can meaningfully improve your total returns.

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

Normally, longer-duration T-Bills yield more than shorter ones — you get paid more for waiting longer. This is a normal yield curve.

An inverted yield curve happens when short-term T-Bills yield more than long-term ones. This occurred in 2022–2023 when 4-week T-Bills were briefly yielding more than 52-week T-Bills.

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

Rolling over means you buy a short-duration T-Bill, and when it matures, you immediately buy another one. Locking in means you buy a longer-duration T-Bill and hold it to maturity.

Best Strategy — The T-Bill Ladder

If you're not sure which duration to pick — or want the benefits of both flexibility and yield — a T-Bill ladder is the answer most experienced investors use.

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