Connecticut residents pay roughly 3%–6.99% state income tax on CD interest, depending on bracket. The best CD rates available to CT residents reach approximately 4.44% APY through FDIC-insured online banks. Connecticut’s income tax environment makes it worth comparing CDs to Treasury bills, which are exempt from CT state income tax.
Rates shown are as of September 2026 and change frequently. Verify current rates directly with the institution before opening.
Best CD Rates Available to Connecticut Residents (September 2026)
| Institution | Type | 12-Month APY | Min. Deposit |
|---|---|---|---|
| Online banks (top-rate) | Online | 4.30–4.44% | $0–$10,000 |
| Ion Bank | CT community bank | 3.25–3.75% | $1,000 |
| Sikorsky Financial CU | CT credit union | 3.25–3.75% | $500 |
| Salisbury Bank | CT/NY community bank | 3.00–3.50% | $1,000 |
| Traditional big banks | National bank | 0.01–1.00% | $1,000+ |
Connecticut State Income Tax on CD Interest
Connecticut uses a progressive income tax structure ranging from roughly 3% at the lowest bracket to 6.99% at the highest. Confirm the exact current-year bracket thresholds at portal.ct.gov/DRS, since precise dollar thresholds are subject to periodic adjustment.
Illustrative after-tax yield on a 4.35% CD for a typical CT resident in the ~5.5% bracket (22% federal + 5.5% CT):
- Total marginal rate: ~27.5%
- After-tax yield: ~3.15%
T-Bills vs. CDs for Connecticut Residents
| 12-Month CD (top rate) | 1-Year Treasury | |
|---|---|---|
| Gross yield | ~4.35% | ~4.37% (per Fed H.15, Sept 14, 2026) |
| Federal taxable | Yes | Yes |
| CT state taxable (~5.5%, illustrative) | Yes | No |
| After-tax yield (22% federal + 5.5% CT) | ~3.15% | ~3.41% (federal-only) |
The after-tax advantage of Treasuries is meaningful for most CT residents and grows for those in higher brackets.
What $10,000 Earns at Top Available CT Rates
| Term | APY (top rate) | Gross Interest | After-Tax (22% federal + 5.5% CT, illustrative) |
|---|---|---|---|
| 6 months | 4.25% | ~$210 | ~$152 |
| 12 months | 4.35% | ~$435 | ~$315 |
| 2 years | 4.35% | ~$889 | ~$644 |
Figures use the APY compounding convention: A = P(1+APY)^years.
Notable Connecticut Institutions
- Ion Bank — Naugatuck-based; community bank serving CT residents
- Sikorsky Financial Credit Union — Stratford-based; open to current/former Sikorsky/RTX employees and family members; also open to Fairfield County residents through community membership
- Salisbury Bank — Northwestern CT and Dutchess County, NY; relationship pricing for local customers
- People’s United (now M&T Bank) — Bridgeport-based, now merged into M&T Bank; largest CT-origin bank by assets
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