After-Tax MMA Returns at $150K
Patricia Wells in New York earns $150,000. Her MMA at 4.65% APY earns $2,325/year on a $50,000 balance. After federal tax (32%) and New York state tax (6.85%) she keeps 61.15% of the interest — a net $1,422. Meanwhile a 4.50% T-bill (state tax exempt) on the same balance nets $1,555 after just federal tax.
After-tax yield comparison at $150K in New York state
| Option | Gross APY | CA/NY State Tax | Fed Tax 32% | After-Tax Yield | After-Tax on $50K |
|---|---|---|---|---|---|
| MMA (NY) | 4.65% | 6.85% | 32% | 2.85% | $1,422 |
| T-Bill (state exempt) | 4.50% | Exempt | 32% | 3.06% | $1,530 |
| Muni MMF (tax-free) | 3.25% | Exempt | Exempt | 3.25% | $1,625 |
| CD (NY) | 5.10% | 6.85% | 32% | 3.12% | $1,561 |
MMA for Emergency Fund — Non-Negotiable
Despite the tax drag a $150K earner still needs an MMA for their emergency fund. The instant check-writing access and full FDIC insurance make an MMA irreplaceable for emergency-fund purposes regardless of income level. A 3-6 month emergency fund ($45,000–$75,000 at $150K income) should remain in an MMA or HYSA.
Even high earners need liquid emergency funds. The after-tax yield difference between an MMA and T-bills on your emergency fund is approximately 0.20%–0.30% — a few hundred dollars annually. The liquidity and check-writing access are worth more than this marginal yield improvement.
Cash allocation framework at $150K income
| Savings Bucket | Recommended Account | Why | At $150K Balance |
|---|---|---|---|
| Emergency fund 3-6 mo | MMA or HYSA | Instant access check-writing FDIC | $45,000–$75,000 |
| Cash above emergency fund | T-bills or muni MMF | Better after-tax yield | Varies |
| 2-yr goal savings | CD | Rate certainty in falling rate env. | Goal-dependent |
| Long-term wealth | Retirement accounts + brokerage | Superior return potential | Max contributions |
At $150K: When MMA Loses to Alternatives
For amounts above your emergency fund an MMA is rarely the best choice at $150K. T-bills offer better after-tax yields in high-tax states. Municipal bond money market funds offer tax-free interest in very high brackets. For amounts with a 5+ year horizon index fund investing vastly outperforms any deposit account.
- Emergency fund ($45K–$75K): MMA or HYSA — instant liquidity wins
- Surplus cash in high-tax state: T-bills or muni MMF for better after-tax yield
- Defined 6-24 month goal: CD for rate certainty
- 5+ year horizon: index funds for dramatically better expected returns
Calculate Your After-Tax MMA Return at $150K
Enter your state and marginal tax rate to see your real effective MMA yield vs. alternatives.