St. Mary's Credit Union CD & Share Certificate Rates — October 2026
As of October 22, 2026, St. Mary's Credit Union's highest tracked CD (share certificate) rate is 4.20% APY on an 18-month relationship CD ($500 minimum). That is 2.7 times the FDIC national average for 24-month CDs (1.55%). Standard CD rates range from 2.50% to 3.95% APY.
Tracking began .
With $10,000 and no relationship requirement: 3.95% on 18 months
St. Mary's Credit Union CD & share certificate rates
Membership required. Certificates from 3 to 60 months ($500 minimum), with standard, relationship, jumbo and relationship bump-up rate sets. Early withdrawal penalties may apply.
| Term | Product | APY | vs. Treasury | Source | |
|---|---|---|---|---|---|
| 3 months | Relationship Certificate Relationship | $500 | 3.50% | −0.79% | Top 27% of tracked 3-month CDs · Verified October 22, 2026 |
| 3 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.50% | −0.79% | Top 27% of tracked 3-month CDs · Verified October 22, 2026 |
| 3 months | Certificate | $500 | 3.35% | −0.94% | Top 31% of tracked 3-month CDs · Verified October 22, 2026 |
| 3 months | Jumbo Certificate | $100,000 | 3.35% | −0.94% | Top 31% of tracked 3-month CDs · Verified October 22, 2026 |
| 6 months | Relationship Certificate Relationship | $500 | 3.75% | −0.65% | Top 32% of tracked 6-month CDs · Verified October 22, 2026 |
| 6 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.75% | −0.65% | Top 32% of tracked 6-month CDs · Verified October 22, 2026 |
| 6 months | Certificate | $500 | 3.60% | −0.80% | Top 40% of tracked 6-month CDs · Verified October 22, 2026 |
| 6 months | Jumbo Certificate | $100,000 | 3.60% | −0.80% | Top 40% of tracked 6-month CDs · Verified October 22, 2026 |
| 9 months | Relationship Certificate Relationship | $500 | 3.85% | −0.63% | Top 33% of tracked 9-month CDs · Verified October 22, 2026 |
| 9 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.85% | −0.63% | Top 33% of tracked 9-month CDs · Verified October 22, 2026 |
| 9 months | Certificate | $500 | 3.70% | −0.78% | Top 48% of tracked 9-month CDs · Verified October 22, 2026 |
| 9 months | Jumbo Certificate | $100,000 | 3.70% | −0.78% | Top 48% of tracked 9-month CDs · Verified October 22, 2026 |
| 12 months | Relationship Certificate Relationship | $500 | 3.95% | −0.62% | Top 30% of tracked 12-month CDs · Verified October 22, 2026 |
| 12 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.95% | −0.62% | Top 30% of tracked 12-month CDs · Verified October 22, 2026 |
| 12 months | Certificate | $500 | 3.80% | −0.77% | Top 38% of tracked 12-month CDs · Verified October 22, 2026 |
| 12 months | Jumbo Certificate | $100,000 | 3.80% | −0.77% | Top 38% of tracked 12-month CDs · Verified October 22, 2026 |
| 15 months | Relationship Certificate Relationship | $500 | 4.10% | −0.55% | Verified October 22, 2026 |
| 15 months | Relationship Jumbo Certificate Relationship | $100,000 | 4.10% | −0.55% | Verified October 22, 2026 |
| 15 months | Certificate | $500 | 3.85% | −0.80% | Verified October 22, 2026 |
| 15 months | Jumbo Certificate | $100,000 | 3.85% | −0.80% | Verified October 22, 2026 |
| 18 months | Relationship Certificate Relationship | $500 | 4.20% | −0.52% | Top 17% of tracked 18-month CDs · Verified October 22, 2026 |
| 18 months | Relationship Jumbo Certificate Relationship | $100,000 | 4.20% | −0.52% | Top 17% of tracked 18-month CDs · Verified October 22, 2026 |
| 18 months | Certificate | $500 | 3.95% | −0.77% | Top 32% of tracked 18-month CDs · Verified October 22, 2026 |
| 18 months | Jumbo Certificate | $100,000 | 3.95% | −0.77% | Top 32% of tracked 18-month CDs · Verified October 22, 2026 |
| 24 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.70% | −1.17% | Top 39% of tracked 24-month CDs · Verified October 22, 2026 |
| 24 months | Relationship Certificate Relationship | $500 | 3.45% | −1.42% | Top 52% of tracked 24-month CDs · Verified October 22, 2026 |
| 24 months | Jumbo Certificate | $100,000 | 3.45% | −1.42% | Top 52% of tracked 24-month CDs · Verified October 22, 2026 |
| 24 months | Certificate | $500 | 3.20% | −1.67% | Top 59% of tracked 24-month CDs · Verified October 22, 2026 |
| 30 months | Relationship Bump-Up Certificate Relationship | $500 | 2.75% | −2.16% | Verified October 22, 2026 |
| 30 months | Relationship Bump-Up Jumbo Certificate Relationship | $100,000 | 2.75% | −2.16% | Verified October 22, 2026 |
| 30 months | Bump-Up Certificate | $500 | 2.50% | −2.41% | Verified October 22, 2026 |
| 30 months | Bump-Up Jumbo Certificate | $100,000 | 2.50% | −2.41% | Verified October 22, 2026 |
| 36 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.50% | −1.45% | Top 41% of tracked 36-month CDs · Verified October 22, 2026 |
| 36 months | Relationship Certificate Relationship | $500 | 3.25% | −1.70% | Top 51% of tracked 36-month CDs · Verified October 22, 2026 |
| 36 months | Jumbo Certificate | $100,000 | 3.25% | −1.70% | Top 51% of tracked 36-month CDs · Verified October 22, 2026 |
| 36 months | Certificate | $500 | 3.00% | −1.95% | Top 63% of tracked 36-month CDs · Verified October 22, 2026 |
| 48 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.50% | −1.48% | Top 38% of tracked 48-month CDs · Verified October 22, 2026 |
| 48 months | Relationship Certificate Relationship | $500 | 3.25% | −1.73% | Top 45% of tracked 48-month CDs · Verified October 22, 2026 |
| 48 months | Jumbo Certificate | $100,000 | 3.25% | −1.73% | Top 45% of tracked 48-month CDs · Verified October 22, 2026 |
| 48 months | Certificate | $500 | 3.00% | −1.98% | Top 59% of tracked 48-month CDs · Verified October 22, 2026 |
| 60 months | Relationship Jumbo Certificate Relationship | $100,000 | 3.50% | −1.51% | Top 42% of tracked 60-month CDs · Verified October 22, 2026 |
| 60 months | Relationship Certificate Relationship | $500 | 3.25% | −1.76% | Top 51% of tracked 60-month CDs · Verified October 22, 2026 |
| 60 months | Jumbo Certificate | $100,000 | 3.25% | −1.76% | Top 51% of tracked 60-month CDs · Verified October 22, 2026 |
| 60 months | Certificate | $500 | 3.00% | −2.01% | Top 63% of tracked 60-month CDs · Verified October 22, 2026 |
APY = annual percentage yield. "vs. Treasury" compares each APY with the Treasury yield for the same term on 2026-10-21 (converted to APY). Treasury interest is exempt from state income tax; see the T-bill vs. CD calculator.
What are St. Mary's Credit Union's best CD rates by term?
St. Mary's Credit Union's best rate is 4.20% APY on 18 months, verified October 22, 2026.
- 3 mo3.50%
- 6 mo3.75%
- 9 mo3.85%
- 12 mo3.95%
- 15 mo4.10%
- 18 mo4.20%
- 24 mo3.70%
- 30 mo2.75%
- 36 mo3.50%
- 48 mo3.50%
- 60 mo3.50%
How much interest could a St. Mary's Credit Union CD earn?
Estimated interest at maturity for the displayed institution quotes, before tax or early withdrawal penalties. Each estimate assumes the quoted APY applies to that balance and interest stays deposited. Estimates use known deposit tiers. Upper balance limits and membership, relationship or new-money requirements must be confirmed with the institution; these are conditional estimates, not personalized offers.
$637.17 interest · $10,637.17 at maturity on $10,000.00.
4.20% APY · 18 months · Relationship Certificate · Relationship · verified October 22, 2026.
Before tax; interest remains deposited. Confirm all product conditions. Estimate one-year purchasing power.
| Term | $5,000 | $10,000 | $25,000 | $50,000 |
|---|---|---|---|---|
| 3 months | $43.073.50% APY · Relationship Certificate · Relationship | $86.143.50% APY · Relationship Certificate · Relationship | $215.343.50% APY · Relationship Certificate · Relationship | $430.683.50% APY · Relationship Certificate · Relationship |
| 6 months | $93.143.75% APY · Relationship Certificate · Relationship | $186.293.75% APY · Relationship Certificate · Relationship | $465.723.75% APY · Relationship Certificate · Relationship | $931.443.75% APY · Relationship Certificate · Relationship |
| 9 months | $143.823.85% APY · Relationship Certificate · Relationship | $287.653.85% APY · Relationship Certificate · Relationship | $719.123.85% APY · Relationship Certificate · Relationship | $1,438.243.85% APY · Relationship Certificate · Relationship |
| 12 months | $197.503.95% APY · Relationship Certificate · Relationship | $395.003.95% APY · Relationship Certificate · Relationship | $987.503.95% APY · Relationship Certificate · Relationship | $1,975.003.95% APY · Relationship Certificate · Relationship |
| 15 months | $257.414.10% APY · Relationship Certificate · Relationship | $514.814.10% APY · Relationship Certificate · Relationship | $1,287.034.10% APY · Relationship Certificate · Relationship | $2,574.054.10% APY · Relationship Certificate · Relationship |
| 18 months | $318.584.20% APY · Relationship Certificate · Relationship | $637.174.20% APY · Relationship Certificate · Relationship | $1,592.924.20% APY · Relationship Certificate · Relationship | $3,185.844.20% APY · Relationship Certificate · Relationship |
| 24 months | $350.953.45% APY · Relationship Certificate · Relationship | $701.903.45% APY · Relationship Certificate · Relationship | $1,754.763.45% APY · Relationship Certificate · Relationship | $3,509.513.45% APY · Relationship Certificate · Relationship |
| 30 months | $351.072.75% APY · Relationship Bump-Up Certificate · Relationship | $702.142.75% APY · Relationship Bump-Up Certificate · Relationship | $1,755.362.75% APY · Relationship Bump-Up Certificate · Relationship | $3,510.712.75% APY · Relationship Bump-Up Certificate · Relationship |
| 36 months | $503.523.25% APY · Relationship Certificate · Relationship | $1,007.033.25% APY · Relationship Certificate · Relationship | $2,517.583.25% APY · Relationship Certificate · Relationship | $5,035.153.25% APY · Relationship Certificate · Relationship |
| 48 months | $682.383.25% APY · Relationship Certificate · Relationship | $1,364.763.25% APY · Relationship Certificate · Relationship | $3,411.903.25% APY · Relationship Certificate · Relationship | $6,823.803.25% APY · Relationship Certificate · Relationship |
| 60 months | $867.063.25% APY · Relationship Certificate · Relationship | $1,734.113.25% APY · Relationship Certificate · Relationship | $4,335.283.25% APY · Relationship Certificate · Relationship | $8,670.573.25% APY · Relationship Certificate · Relationship |
How St. Mary's Credit Union compares
Compare the displayed terms, minimums and quote locations. Membership, relationship and new-money conditions may apply. Institution quotes below use the exact 548-day term. Regional peers quote a shared operating state; nationwide best is limited to our tracked sample.
This quote ranks 51 of 295 tracked institutions with fresh 548-day quotes (ties share a rank). Each other institution contributes its highest APY for that exact term; minimums and eligibility can differ.
| Institution / benchmark | Term | Minimum | Who can open | APY | Verified / source date |
|---|---|---|---|---|---|
| St. Mary's Credit Union (this institution)Relationship Certificate · Relationship | 18 months | $500 | Membership required · branches in CT, MA | 4.20% | October 22, 2026 |
| Popular DirectCD · Standard | 18 months | $10,000 | Available nationwide | 4.75% | October 22, 2026 |
| E*TRADE (Morgan Stanley Private Bank)Bank CD · Standard | 18 months | Not stated | Available nationwide | 4.55% | October 22, 2026 |
| BarclaysOnline CD · Standard | 18 months | Not stated | Available nationwide | 4.50% | October 22, 2026 |
| Kirtland Federal Credit Union (highest tracked APY for this term)18-Month Limited-Time Share Certificate · Promotional | 18 months | $500 | Membership required · branches in NM | 5.12% | October 22, 2026 |
| Treasury (APY-equivalent) | 18 months (term-matched estimate) | Depends on purchase method | Federal; interest exempt from state income tax | 4.72% | 2026-10-21 |
Rate changes
See changes across all tracked institutions
No changes since we started tracking St. Mary's Credit Union on October 22, 2026.
About St. Mary's Credit Union
- Legal name
- St. Mary'S Credit Union
- Regulator ID
- NCUA 67864
- Headquarters
- Marlborough, MA
- Available in
- CT, MA
- Total assets
- $1.0 billion
- Also known as
- Website
- www.stmaryscu.org
Source: rates read from https://www.stmaryscu.org/services/tools/rates.html. See the page text we read.
Frequently asked questions
What is the highest CD rate at St. Mary's Credit Union?
Among the rates we track, 4.20% APY on an 18-month relationship CD, as of October 22, 2026.
What is the minimum deposit for a St. Mary's Credit Union CD?
The lowest minimum we found is $500; jumbo and higher balance tiers start at up to $100,000.
How does St. Mary's Credit Union's best CD rate compare with Treasury yields?
4.20% APY is −0.52% versus the 18-month Treasury yield of 4.72% (APY-equivalent) on 2026-10-21. Treasury interest is also exempt from state income tax.
Is 4.20% a good CD rate?
It is 2.7 times the FDIC national average for a similar term (1.55% as of 2026-10-19), which is a deposit-weighted average across all U.S. banks and credit unions. Online banks and promotional CDs often pay several times the national average.
Are St. Mary's Credit Union CDs insured?
St. Mary's Credit Union is a federally insured credit union (NCUA 67864). Share certificates are insured by the NCUA up to $250,000 per member, per ownership category.
What is a share certificate at St. Mary's Credit Union?
A share certificate is the credit union equivalent of a bank CD: a term deposit that pays a stated yield when its conditions are met. Membership requirements, minimum deposits and early withdrawal terms depend on the credit union and product.
How often is this page updated?
We check St. Mary's Credit Union's rate page every day. The rates above were last verified on October 22, 2026.
More credit union certificate rates
Rates are copied from St. Mary's Credit Union's website and may change at any time. Confirm terms, minimums and eligibility with St. Mary's Credit Union before opening an account. This page is not financial advice.