JULIETTE FAIRLEY, NEW YORK, N.Y.

For the self-employed, the retirement plan of choice is usually a Simplified Employee Pension (SEP), says Kyra Morris of Morris Financial Concepts in Mount Pleasant, S.C. It’s just like an IRA, except that you can put more money in. There’s zero government paperwork. You open a SEP with a stockbroker, bank or mutual-fund group (your current fund group will have one) and report the contribution on your tax return.

Contributions to SEPs are tax-deductible; you can put in any amount each year, up to your personal maximum; the earnings accumulate tax-deferred; there’s generally a 10 percent tax penalty on money withdrawn before you reach 59 1/2.

Here’s how to figure your maximum contribution: take your net self-employment earnings after expenses, subtract one half of your Social Security tax and multiply the remainder by 0.13043. No matter how much you earn, however, you can’t contribute more than $24,000 this year (that ceiling rises with inflation). For a good, free IRS booklet, call 800-TAX-FORM and ask for Publication 560, ““Retirement Plans for the Self-Employed.''

QUESTION: I was out of town when my husband filed our joint 1992 tax return. I gave him permission to sign my name only if he had the $15,000 to pay (he was making almost all our joint income). He said he did, which turned out not to be true. I’ve been filing separately since then. But my soon-to-be-ex-husband never paid, so my tax refunds are always seized for that old delinquency. Is there any way I can get out of paying? Am I responsible for any other of his debts? I’ve moved out of our home, but he is still living there.

NAME WITHHELD

You’re not allowed to change a joint return to a separate one. But tax expert Tom Ochsenschlager of Grant Thornton in Washington, D.C., says you could try filing an amended return for 1992, attached to a letter explaining that the first return carried an invalid signature. Also, ask for your refunds back.

It’s not that easy, of course. The IRS will start asking questions, and you’ll have to prove that that’s not your signature. It’s not at all clear how this might turn out.

To protect your refunds, you could reduce your withholding, leaving the IRS no money to intercept. But the government can come after you in other ways, and meanwhile the interest you owe will compound.

You’re liable for any debts you signed for, such as the mortgage on the home and purchases on a joint credit card, but not for debts run up under your ex’s name alone. Don’t let him keep the house unless the lender agrees to put the mortgage in his name (it has to be the lender; the divorce judge can’t decide). If you’re still on the loan and he’s late with his payments, that blotch will show on your credit report. If he doesn’t pay at all, the bank will come after you–even though the house is his.

QUESTION: I’m a podiatrist, married with two children, and carry a health-insurance policy with a high deductible. I’d like to open a Medical Savings Account but can’t find an institution that’s offering one. I hope the government hasn’t been trying to pull the wool over my eyes.

WILLIAM LOCKNER, MINNEAPOLIS, MINN.

The private sector is working on Medical Savings Accounts (MSAs), but it takes time to activate them. Kenneth Feltman, executive director of the Employers Council on Flexible Compensation (ECFC) in Washington, D.C., thinks we’re six to 12 months away from aggressive marketing of the product.

MSAs are for self-employeds or people who work for companies with 50 or fewer employees and no medical plan. You buy a high-deductible health-insurance policy, agreeing to pay, say, the first $1,500 or $4,500 in annual medical expenses yourself, before the policy clicks in. At the same time, you open a tax-deductible MSA–available, at present, from just a few insurers and banks.

Every year, you can stash a certain sum in the MSA and tax-deduct it. That money is available, tax free, to pay medical bills that your policy doesn’t cover. If you’re healthy, your savings can grow into a tidy pile. You can even use the account for nonmedical expenses, although the withdrawals would then be taxed.

Milwaukee-based Time Insurance Co. offers policies in Minnesota. For sources in other states, readers can call the ECFC’s MSA-request line at 202-842-3232. Alternatively, you could buy a high-deductible policy from any insurer, then open a free-standing bank MSA (the ECFC has a list)–but compare the bank’s interest rates and fees before you decide. Also, compare the insurance policy’s worst-case out-of-pocket expenses and premiums with what you’d pay under a traditional health plan. Newer isn’t always better. Sometimes MSAs cost more.

Send your questions to Jane Bryant Quinn, NEWSWEEK Focus: On Your Money, 251 West 57th Street, New York, N.Y. 10019. Letters can be answered only in the column.