Treasury Bills (T-Bills) Explained

The 91-Day Investment Most Indians Have Never Heard Of

What is a Treasury Bill? A Treasury Bill (T-Bill) is a short-term government security issued by the RBI on behalf of the Government of India, with maturities of 91, 182, or 364 days. It carries no coupon interest; instead, it's sold at a discount to its face value, and the difference between what you pay and what you receive at maturity is your return.

There's an investment in India with zero default risk, a return you know before you invest a single rupee, and a holding period shorter than most people's phone contracts.

Almost nobody talks about it. No billboard, no salesperson calling you, no ad campaign. It just quietly exists, doing exactly what it promises, while the financial industry's marketing budget goes toward mutual funds and insurance instead.

Once you understand how a T-bill actually works, you'll wonder why it isn't the first thing anyone recommends to a nervous first-time investor.

T-Bills at a Glance

• Issuer: Reserve Bank of India, on behalf of the Government of India
• Tenures available: 91 days, 182 days, 364 days
• Return mechanism: Discount to face value, no periodic coupon
• Credit risk: Effectively zero sovereign-backed
• Minimum investment: ₹10,000 via RBI Retail Direct
• Taxation: Depends on holding period and treatment see the taxation section below
• Best suited for: Investors parking money for a known, short-term goal

How a T-Bill Actually Works

Imagine the government needs ₹100 for exactly 91 days. Instead of asking you for ₹100 and promising to pay it back with interest later, it does something different.

It asks you for ₹98 today, and promises to hand back exactly ₹100 in 91 days.

You've made ₹2 in 91 days on your ₹98. No interest rate was quoted to you upfront. No coupon was paid into your account halfway through. The entire return was baked into the price you paid.

This is called buying "at a discount," and it's the defining feature that separates T-bills from most bonds. A bond pays you interest along the way. A T-bill pays you nothing along the way and instead sells to you for less than what you'll get back closer in spirit to a promissory note than a traditional interest-bearing loan.

A more realistic picture, at ₹10,000:

Invest ₹10,000 → Receive approximately ₹10,170 at maturity (illustrative, based on a roughly 91-day T-bill yielding around 7% annualized) Profit: approximately ₹170

The exact number moves with that week's auction yield but the shape of it stays the same: you know your payout on day one, not just an estimate of it.

Why the Discount Model Exists

Governments don't only need money for years at a time. Sometimes they need cash for weeks, to smooth short-term gaps between tax collection and spending. Issuing a full bond for a 91-day need would be unnecessarily heavy machinery for a light job.

A discounted instrument is simpler: one transaction, one payout, done.

What T-Bill Yields Actually Look Like

Yields move with RBI policy, systemic liquidity, and inflation expectations, so the exact number shifts from one week's auction to the next. Rather than quoting a figure that will age quickly, the right habit is this: check the latest RBI auction results before investing. That's the only number that reflects what you'd actually earn today, not what you might have earned last quarter.

Why Yields Change Week to Week

This is one of the most common beginner questions, and it deserves a real answer.

RBI policy. When the RBI raises its repo rate, short-term borrowing across the economy gets more expensive, and T-bill yields tend to rise. When it cuts rates, yields tend to fall.

Systemic liquidity. If there's a lot of surplus cash in the banking system chasing few safe places to park it, demand for T-bills rises, pushing yields down. When liquidity is tight, the opposite happens.

Inflation expectations. If investors expect inflation to rise, they demand a higher yield to compensate for the erosion in real purchasing power, pushing T-bill yields up.

Demand at auction. Each week's auction has its own dynamics a heavily oversubscribed auction can push yields slightly lower than the previous week, even with no major policy change.

Calculating Your Actual Return

The return on a T-bill is your annualized yield a ₹2 gain on ₹98 over 91 days needs to be converted into a "per year" figure before you can compare it to anything else, from a savings account to an FD.

Face value: ₹100 Purchase price: ₹98 Tenure: 91 days Absolute gain: ₹2 over 91 days

Annualized Yield = (Gain ÷ Purchase Price) × (365 ÷ Tenure in days) × 100

(2 ÷ 98) × (365 ÷ 91) × 100 ≈ 8.19% annualized yield

Common mistake: Assuming an "8% T-bill" means you earn 8% on your money over whatever period you're holding it. If you're holding the 91-day version, you earn roughly a quarter of that the annualized figure is already stretched to represent a full year.

Auctions: How Often, and Are You Guaranteed Allotment?

The RBI generally conducts T-bill auctions weekly, according to its published auction calendar the specific day and settlement timeline can shift, so it's worth checking the current calendar on the RBI's website rather than assuming a fixed day.

Retail investors using RBI Retail Direct participate as "non-competitive bidders." This matters practically: you don't need to guess or specify a price. You simply indicate how much you want to invest, and you're allotted T-bills at the weighted average yield determined by the auction's competitive bidders (typically large institutions).

Is allotment guaranteed? For non-competitive retail bidders, allotment is generally assured up to the notified limit for that category, though the exact amount you receive depends on total demand within that quota for the specific auction.

How to Actually Apply: A Step-by-Step Walkthrough

1. Open an RBI Retail Direct account free, done online with your PAN and bank details.
2. Complete KYC, a one-time verification process.
3. Choose the upcoming T-bill auction you want to participate in, and the tenure (91, 182, or 364 days).
4. Enter your investment amount, in multiples of ₹10,000, as a non-competitive bid.
5. Funds are debited from your linked bank account around the auction date.
6. Receive your allotment at the weighted average yield, credited to your Retail Direct account after settlement.
7. Hold until maturity for automatic redemption, or sell earlier via the secondary market on NSE or BSE.

Taxation: What the Law Actually Says

Here's where precision matters more than a confident one-line answer.

For T-bills held to maturity, the discount you earn is commonly treated as interest income, taxable at your individual slab rate under the Income Tax Act's provisions for income from other sources. If you sell a T-bill in the secondary market before maturity, the transaction may instead be evaluated for capital gains treatment, since it involves a market sale rather than redemption at face value.

This distinction and its exact application to your situation can depend on factors like whether you're an individual investor or hold T-bills as a trading asset. This is genuinely worth confirming with a chartered accountant or tax advisor, especially if you're investing meaningful amounts, rather than relying on any single article, including this one, as the final word.

A worked example, for illustration only:

You invest ₹10,000, and receive ₹10,170 at maturity. Gain = ₹170

If taxed as interest income at the 30% slab rate: Approximate tax = ₹51 Approximate net gain = ₹119

The exact figure depends on your specific tax treatment and slab treat this as a way to understand the mechanism, not a substitute for actual tax advice.

Selling Before Maturity: What Actually Happens to the Price

T-bills can be sold in the secondary market via NSE or BSE before maturity. Here's why the price movement tends to be small.

If interest rates rise after you've bought your T-bill, newer T-bills start offering better yields, making yours comparatively less attractive so its price dips slightly to stay competitive. But because a T-bill matures in at most 364 days, there's a hard limit on how much time and therefore how much rate movement can work against you. A 30-year bond can swing sharply on the same rate move; a 91-day T-bill barely flinches, because it's almost at its finish line already.

T-Bills vs Bonds vs FDs vs Liquid Funds vs Savings Accounts

The sovereign guarantee is the meaningful difference against FDs specifically: a bank FD is protected only up to ₹5 lakh via DICGC insurance, regardless of the amount deposited, while a T-bill carries the Government of India's full backing with no such ceiling.

Who Should NOT Invest in T-Bills

Anyone needing same-day access to their money. T-bills settle on a fixed date and aren't built for emergency funds you might need tomorrow. A savings account or liquid fund serves that job better.

Investors seeking regular monthly income. T-bills pay nothing until maturity, no periodic payout. A bond with periodic coupons or a monthly-payout FD fits that need better.

Anyone chasing long-term wealth creation. A T-bill isn't going to compound your way to a large retirement corpus. It's a parking spot for money with a known short-term destination, not a growth engine.

How to Actually Buy a T-Bill in India

RBI Retail Direct. Any resident individual can open a free account with the RBI, complete KYC, and bid as a non-competitive bidder in the weekly primary auction, starting from ₹10,000.

Through banks and licensed intermediaries. Some banks and SEBI-registered platforms also facilitate T-bill purchases, generally following the same underlying RBI auction mechanism.

Secondary market. Already-issued T-bills can be bought and sold before maturity via NSE or BSE, for investors who don't want to wait for the next auction.