The T-Bill Emergency Fund: A Rolling 91-Day Ladder That Beats Your Savings Account
The standard emergency-fund advice, keep six months of expenses in a savings account, quietly costs real money. ₹6 lakh at a big bank’s ~3% savings rate earns ₹18,000 a year, while 91-day T-bills pay around 5.3%. That’s a ₹14,000 annual gap that grows with your fund, for credit that’s better than the bank’s. Here’s a system that captures most of the gap without giving up real-world access.
The architecture: three layers
Layer 1, instant, 2–4 weeks of expenses. Savings account or sweep-in FD. This covers the burst pipe tonight.
Layer 2, T+1, 1–2 months. A liquid fund, bridging anything while Layer 3 cycles. (T-bill vs liquid fund trade-offs here.)
Layer 3, the rolling T-bill ladder. The bulk of the fund, in 91-day T-bills maturing every couple of weeks, indefinitely.
Layer 3 works because an emergency rarely needs all the money on the same day. It needs some now, which Layers 1 and 2 cover, and the rest over the following weeks, which is what a rolling ladder delivers at sovereign credit and no expense ratio.
Building the ladder
Say Layer 3 gets ₹4.8 lakh. Split it into six slices of ₹80,000, since auction bids round to ₹10,000 (RBI Retail Direct minimums).
- Week 1: bid one slice in the weekly 91-day auction. Wednesdays, non-competitive, so you get the weighted-average price.
- Weeks 3, 5, 7, 9 and 11: repeat with the next slice.
- Week 14 onward: slice 1 matures and the money lands in your bank automatically. Re-bid it that week. From here the machine runs itself, with something maturing every couple of weeks, and each roll taking two minutes on the app.
Since August 2025 you can hand the rolling over to Retail Direct’s auto-bid rules, which place auction bids and reinvest maturities on a schedule you set. Worth setting up once the ladder is built and you’re bored of it. Building the first cycle by hand is still the better way to learn what you own.
You can design your own slice and spacing combination in the ladder builder, and convert any auction price to its yield in the T-bill calculator.
When an emergency hits, spend Layers 1 and 2, then stop rolling. Each maturing slice turns into cash every fortnight. A full ₹6L fund frees roughly ₹80k immediately plus ₹80k every two weeks, which outpaces how fast most emergencies actually consume money. Hospital deposits are the exception, and that’s what Layer 1 is for.
What it earns
At recent cut-offs of roughly 5.2–5.3% on 91-day bills, ₹4.8L in Layer 3 earns about ₹25,000 a year against ₹14,400 in a 3% savings account. Post-tax the gap narrows, since T-bill gains are taxed at slab and so is savings interest beyond the small 80TTA deduction. Call it ₹8,000–12,000 a year per ₹5 lakh, with better credit behind it. Not life-changing money, but it’s permanent and free.
Honest limitations
- It isn’t same-day money. That’s what Layers 1 and 2 exist for. Never put an entire emergency fund in Layer 3.
- Setup takes about 12 weeks of two-minute weekly actions. Maintenance afterwards is trivial, but the ramp needs mild discipline.
- Rates float. Each roll reprices to the current auction, so in a cutting cycle your yield drifts down. Savings accounts fall too, just from a lower starting point.
- Rolling by hand is an obligation, if you choose to do it by hand. Miss rolls chronically and Layer 3 decays into idle bank balance. Auto-bid rules remove this limitation almost entirely, which is the strongest argument for using them. If you’d rather not automate and know you won’t keep up the manual roll, a liquid fund is the self-honest choice: costlier, zero effort.
Who this suits
It works well for funds above roughly ₹3 lakh, for people already using RBI Retail Direct for other sovereign buying, and for anyone whose emergency fund doubles as opportunity cash, since a maturing slice is also dry powder.
Skip it if your fund is under about ₹2 lakh, where the absolute gain doesn’t repay the ritual. Skip it too if only one person in the household understands the system. An emergency fund your spouse can’t operate is a design failure, so either document the layers properly or stay simpler.
FAQ
Why 91-day and not 364-day bills? The 364s yield more, but a slice locked for a year defeats the purpose. If your fund is large, a hybrid works: most in 91s, a tail in 182s and 364s to capture some of the slope.
Sweep-in FD or this? Sweep FDs are good Layer 1 and 2 tools, instant and at roughly FD rates. They lose to T-bills on credit (bank versus sovereign, and DICGC caps) and usually on rate for the bulk layer.
Can I do this through a broker instead of Retail Direct? Partly. Some brokers route T-bill auction orders for a small fee. The economics survive, but check the fee per roll, because you’ll be rolling 26 times a year.
Educational content, not investment advice. Tax rules current for FY 2026-27 to the best of our knowledge, but verify with a professional before acting. See the full disclaimer.