The popular IRA has some new wrinkles that bear watching

In less than three years, the individual retirement account (IRA) has turned out to be quite unusual for something coming out of Washington: Almost everybody agrees it was a good idea.

More than $119 billion was parked in IRAs by the end of April, says Wesley Howard, editor of the IRA Reporter, a Cleveland newsletter. The IRA concept is so well liked it is often mentioned as a way to help families save for first-home down payments or college tuition - that is, until the size of the federal deficit is remembered.

Still, Congress likes to tinker, so there are some changes that people with IRAs, and the financial service firms handling them, need to be aware of. Also, there are some strategies that financial planners have been encouraging as ways to make more effective use of them. This year's tax law includes a tighter definition of ''deadline'' as it applies to IRA payments, a more liberal use of alimony payments for meeting the IRA income test, and the ability to move pension-plan assets into an IRA.

Until the new tax law, people getting an extension of their filing date past the usual April 15 deadline could wait until their new deadline to make the previous year's IRA contribution. So this year, for example, it was possible to get an extension to Aug. 15, send in the return two or three months before then, and use any refund to help pay for the 1983 IRA that had been claimed on the return. As long as the Internal Revenue Service clerks and the post office cooperated to get the refund back on time, everything was fine.

Now, even with their help, you can't do this. The new law says IRA contributions must be made by the regular filing deadline, which is April 15 for most people. You can still get extensions for filing the return, but you'll have to make the IRA payment by mid-April.

In another move to tighten the use of IRAs, the tax law clarifies the authority of the Treasury Department to require IRA trustees or issuers to report all contributions. The effect of this, which carries a $50 penalty per violation, is to help the IRS find out if taxpayers are really making the IRA contributions they claim, says Joseph Walshe, a senior consultant in the actuarial, benefits, and compensation group at Coopers & Lybrand, the accounting firm.

These tightening moves have been balanced by at least two liberalizing measures. One of them permits alimony payments to be used more fully for IRA contributions. Before, a divorced woman, for instance, could put only $1,125 of the money she received in alimony into her IRA. Now, she can treat $2,000 of alimony as compensation for IRA contribution purposes, giving her the opportunity to put aside more for her retirement. The effective date of this provision is next Jan. 1, so the higher limit applies to all alminony received after then.

Another change concerns partial distributions of assets in pension or profit-sharing plans. Sometimes, Mr. Walshe says, people feel they can get better performance by investing part of their pension-plan assets themselves, instead of having the employer-selected manager do it. ''Previously, if you got a partial distribution from a company's retirement plan, you couldn't roll it over,'' he said. ''You had to get all of it to roll over part of it.''

The new tax law permits you to take 50 percent of the money in the account, but you cannot make any subsequent early withdrawals. Here again, however, the tax law shows some teeth: Once you have made a partial withdrawal, neither the withdrawn money nor the remaining part is eligible for 10-year forward averaging , a technique that greatly reduces the tax burden of a pension plan at retirement.

Rollovers can also be made from one IRA to another. This is not something that came with the new tax bill, but it is getting more attention now that people have had some time to see how well their IRAs are doing. If your IRA doesn't seem to be performing well, you can move the money somewhere else without penalty, just so you play by two rules:

First, as long as you do not take possession of the funds, you can make a direct transfer from one IRA to another as often as you like. You can, for instance, instruct your bank (if that is where you have the IRA) to wire the money to a brokerage or mutual fund, where a new IRA has been set up. Or, if you have more than one IRA, you can shift assets fom one to another in a similar manner.

Second, if you do take possession of the money, you have 60 days to find a new IRA home for it, without having to pay taxes or penalties.

A final IRA tip comes from Fred Kerpen, a financial planner in New York. Often, he says, insurance company salespeople will recommend an annuity as a good place for an IRA. This, Mr. Kerpen says, is both a waste of effort and money. The returns from an annuity are already tax-deferred, so there is no need to use it for a tax-deferred IRA. If you have more than $2,000 that you can put toward retirement in a year, an annuity may be a good place for the additional money; but don't start it until after you've reached the IRA limit.

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