FDLXX vs SPAXX: Which Should You Pick?
Fidelity's Treasury-only fund against its default core. FDLXX keeps its state-tax exemption in CA, CT and NY; SPAXX loses it. Switching is free at a $1 NAV. With a calculator.
Both are Fidelity money market funds at a $1.00 share price with the same 0.42% expense ratio. SPAXX is the default core and holds Treasuries plus repurchase agreements; FDLXX holds Treasuries only and has to be bought separately. That one difference decides the state-tax treatment.
Quick answer
FDLXX, for any cash that sits, in any state with an income tax. For 2025 Fidelity reported 98.67% of FDLXX’s income as Treasury interest and marked it as passing the California, Connecticut and New York quarterly test; SPAXX reported 50.90% and missed the test, so those three states tax all of it. For one modeled California saver at 32% federal and 9.3% state, FDLXX came out about $173 a year ahead on $50,000, and roughly $60 ahead in a 5% state. Both funds hold a $1.00 price, so there is no gain to realize and nothing to pay when you switch, and Fidelity draws on FDLXX automatically to cover purchases. The only cost is remembering to buy it, since new deposits still land in SPAXX.
| FDLXX | SPAXX | |
|---|---|---|
| Holdings | US Treasuries only | Treasuries and repurchase agreements |
| 7-day yield, Aug 31 2026 | 3.39% | 3.33% |
| Expense ratio | 0.42% | 0.42% |
| 2025 income from US gov't securities | 98.67% | 50.90% |
| CA / CT / NY quarterly test | Passed | Missed |
| Core position eligible | No; bought separately | Yes; the default |
| Covers purchases automatically | Yes, auto-liquidated | Yes, it is the core |
| Share price | $1.00 | $1.00 |
Who should pick which
Buy FDLXX with stored cash if your state has an income tax, and especially in California, Connecticut or New York, where SPAXX gets no exemption at all.
Leave it in SPAXX in a state with no income tax, where the only difference is six basis points of yield, or inside an IRA, where state tax never applies.
Does this decision matter?
Yields are Fidelity’s published month-end 7-day yields for August 31, 2026. Government-securities percentages are for tax year 2025 and are republished each January.
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