Cash-secured put vs T-bills: is the premium worth the stock risk?
A Treasury bill pays interest on your cash with almost no risk. A cash-secured put pays a premium on the same cash, but you may have to buy a falling stock. So the T-bill rate is the hurdle. A put that barely clears it pays you very little for the stock risk you take on.
The short answer
Put your cash in T-bills when the extra premium from a put is small next to the drop you could be forced to buy. Sell the cash-secured put when the premium clears the T-bill interest by enough to pay for that risk, on a stock you'd be fine owning.
A Treasury bill is a short loan to the US government, a year or less. A Cash-secured put means you set cash aside to buy 100 shares and get paid a premium for promising to buy at the strike.
Both start with the same cash. Only one can hand you a stock that's falling.
Side by side
| T-bills | Cash-secured put | |
|---|---|---|
| What pays you | Interest | The premium |
| Known up front | Yes, if held to maturity | The premium, yes; the outcome, no |
| Downside | Very small for US T-bills | The stock can fall far below the strike |
| Upside | The interest | The premium, no more |
| Cash at the end | Back, plus interest | Back plus premium, or 100 shares |
| Effort | Buy and hold | Pick a stock, a strike, a date; manage it |
| Main question | What's the rate? | Is the extra over T-bills worth the stock risk? |
A worked example: one put that clears the hurdle badly, one that clears it well (hypothetical)
Say T-bills pay a hypothetical 4% a year. You have $5,000, enough to secure one $50 put for 30 days.
- T-bill interest for 30 days: $5,000 × 4% × 30 ÷ 365 = about $16.
Now two puts, both $50 strikes, both 30 days:
- Put A, on a calm stock: premium $0.25 ($25). That's about $9 more than T-bills for the month.
- Put B, on a jumpier stock: premium $1.00 ($100). That's about $84 more than T-bills.
Here's how the month ends at three prices, next to simply holding T-bills (before fees):
| Stock at expiry | T-bills | Put A ($0.25) | Put B ($1.00) |
|---|---|---|---|
| $52 | +$16 | Expires: +$25 | Expires: +$100 |
| $49 | +$16 | Assigned at $50: −$100 + $25 = −$75 | Assigned at $50: −$100 + $100 = $0 |
| $44 | +$16 | Assigned: −$600 + $25 = −$575 | Assigned: −$600 + $100 = −$500 |
Put A is the bad deal. In the best case it beat T-bills by $9. At $44 it lost $575, about 35 months of T-bill interest gone in one bad month. You took the full risk of owning the stock for almost nothing extra.
Put B lost too at $44. But it paid $84 over the hurdle for that risk, and it was still even at $49. Whether that's enough is your call. At least the trade was paying you to take it.
Before you sell a put, write down the premium minus what T-bills would pay on the same cash. That's what you're really being paid for the stock risk.
Where the collateral can sit while the put is open
You don't always have to pick one. Depending on your broker, the cash behind a put might:
- Sit as cash and earn the broker's cash rate, which can be low.
- Sit in a money market fund that you can sell quickly.
- Sit in T-bills that some brokers count toward the cash needed for a put.
If your collateral can earn close to the T-bill rate while it secures the put, the premium is on top of that interest, not instead of it. That changes the math a lot. Broker rules vary, so check yours as of October 2026: what counts as collateral for a cash-secured put, and what interest idle cash earns.
On assignment, you need cash to pay for the shares when the trade settles. If the collateral sits in T-bills or a fund, ask your broker how it handles that: some lend against it for a day or two, some need you to sell first. See keeping cash aside for assignment.
In Canada, cash-secured puts in a TFSA or RRSP depend on the broker, and options permissions differ by broker. Canadian T-bills and high-interest savings funds play the same "hurdle" role there.
Which should you choose?
| Choose T-bills if… | Choose the cash-secured put if… |
|---|---|
| The premium barely beats the interest | The premium clears the interest by a clear margin |
| You wouldn't want the stock at the strike | You'd be fine owning the stock at the strike |
| You need the cash on a known date | You can hold shares for a while if assigned |
| You don't want to manage a position | You'll check it and have a plan for a drop |
Running the wheel strategy means you've chosen the put side, so every put should clear this hurdle. The options strategy comparison chart shows the capital each strategy ties up, and the cash-secured put calculator runs a premium on your numbers.
Questions
Are cash-secured puts better than T-bills?
Not automatically. A put pays more only when nothing goes wrong. If the stock falls below the strike minus the premium, you lose money that T-bills would never have lost. Compare the extra premium to the risk.
Can I use T-bills as collateral for cash-secured puts?
Some brokers allow it or count T-bills toward the cash needed, and others don't. Check your broker's rules on collateral for cash-secured puts.
Does my cash earn interest while it secures a put?
It depends on the broker. Some pay interest on cash or let you hold a money market fund, and some pay little on idle cash. That interest is part of what the put has to beat.
What happens to my collateral if I'm assigned?
It pays for the 100 shares when the trade settles. If it's in T-bills or a fund, your broker may need you to sell them, or may cover you briefly. Ask before your first assignment.
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