(MONEY Magazine) – The Health Savings Accounts (HSAs) created by the new Medicare law will let folks under age 65 who are in high-deductible insurance plans ($1,000 or more for individuals, $2,000 for families) save, invest and spend money tax-free for out-of-pocket medical expenses. But even though the accounts go into effect Jan. 1 and insurers like Aetna, Fortis Health and UnitedHealthcare are gearing up to offer them, don't expect HSAs to become widely available soon--insurers and employers are still waiting for guidance from the Treasury Department on how to administer them. Small business owners and the self-employed may see HSAs first. Fortis is planning to offer an HSA to individuals with high-deductible plans in January. Aetna expects to be ready early in 2004 with an employer version. But, cautions Aetna spokeswoman Betsy Sell, "are employers going to want to go back into the open-enrollment process? Hard to say." --ELLEN McGIRT