Short answer: if you need the money within a year and might need it sooner, a high-yield savings account (HYSA) is usually the simplest choice. If you know the exact date you will spend it, a CD or a Treasury bill can lock in a rate. Treasury bills have one edge the others lack: their interest is exempt from state and local income tax. The best option depends on how sure you are about when you will need the cash.
This is educational content, not financial advice. We do not quote current rates because they change weekly; check them before you decide.
The three options at a glance
| High-yield savings | Certificate of deposit (CD) | Treasury bill (T-bill) | |
|---|---|---|---|
| Rate | Variable; the bank can change it any time | Fixed for the term | Fixed at purchase (set at auction) |
| Access to cash | Anytime, usually a few days to transfer | Early withdrawal penalty | Sell before maturity at market price |
| Safety | FDIC insured up to $250,000 | FDIC insured up to $250,000 | Backed by the U.S. government |
| Taxes | Federal and state | Federal and state | Federal only; exempt from state and local |
| Typical terms | None | 3 months to 5 years | 4 to 52 weeks |
A worked example: $10,000 over 12 months
To keep the math honest we use a hypothetical 4% for all three. At 4% for a year, $10,000 earns about $400 before taxes. The headline rate is the same, so the real differences are:
- HYSA: if the bank cuts the rate to 3% in month six, you earn less. If rates rise, you earn more.
- CD: your 4% is locked. Pull the money out early and you typically lose some months of interest as a penalty. Penalty sizes vary by bank, so read the disclosure before opening.
- T-bill: your return is also locked once you buy. In a state with an income tax, skipping the state tax can make a slightly lower T-bill rate beat a higher CD rate after tax.
The after-tax comparison is easy: multiply the interest by (1 minus your tax rate). Federal-plus-state tax of 30% on $400 leaves $280; federal-only tax of 22% on $400 leaves $312.
Which one fits your situation?
Choose a high-yield savings account if this is an emergency fund or you might need the cash on short notice. Flexibility is worth a slightly lower rate. We cover the savings account versus money market question in this comparison, and how much to keep in this guide.
Choose a CD if you have a known date (a tuition bill, a down payment in 12 months) and you want the rate fixed. A CD ladder, with money spread across 3-, 6- and 12-month terms, gives you cash coming due regularly.
Choose a T-bill if you live in a state with income tax, you are comfortable using TreasuryDirect or a brokerage, and you will hold to maturity.
Mistakes to avoid
- Chasing a top rate at a bank that is not FDIC insured. Check how the $250,000 rule works.
- Locking in a CD with money you may need next month.
- Ignoring renewals. Many CDs auto-renew at whatever the current rate is; set a calendar reminder.
- Keeping your whole cash pile in a checking account that pays almost nothing.
Our take
For most people, the right answer is boring: keep your emergency fund in an HYSA, and use CDs or T-bills only for money with a deadline. The difference between the three is often smaller than the cost of picking wrong and having to break a CD. Decide by your timeline first and the rate second.
Sources: FDIC deposit insurance rules (fdic.gov); TreasuryDirect on Treasury bills (treasurydirect.gov). Example rates are hypothetical. This is educational content, not financial advice.