Many people should have their wills redrawn as a result of the Tax Reform Act of 1976. "Among those who owe estate taxes, 80 to 90 per cent may want to make changes," says Richard B. Covey of the New York law firm, Carter, Ledyard & Milburn.

Even some people who don't owe estate taxes may want to reconsider their bequests. The new law imposes a capital gains tax on property that has increased in value since they bought it, and they may have to make arrangements for getting that tax paid. Property worth up to $60,000 however, is excempt.

Although imposing a broad capital gains liabilty, the Tax Reform Act frees many people from estate taxes. This year, no tax is owed by those with taxable estates under $120,000. That amount gradually rises unitl in 1981, $175,000 will escape tax-free. If you made tax-avoidance moves under the old law, but are now exempt from estate taxes, you'll probably want to take the obsolete provisions out of your will.

People who still find themselves subject to estate tax, and are married have an opportunity to leave more money to their spouse tax-free. It's particularly important to examine this option, since the new higher levels of taxation at death will leave the family much less of the taxable.

Under both the old law and the new one, a man can leave his wife (or vice versa) up to half his estate tax-free. But the new law also gives him the alternative of leaving her up to $250,000 free and clear. if half your estate is worth less than $250,000 you'll want to consider a change.

But just because the $250,000 deduction is there doesn't mean you should automatically use the full amount. Most people will save taxes by taking a different approach.

Each individual estate is entitled ot credit against estate taxes. In 1977, the credit is the equivalent to a $175,000 deduciton. By using the credit before taking the marital deduction, a couple can shelter more of their assets from taxes.

It's advantagious to have the wife own a considerable amount of property. She can then use her own estate credit to set up a tax-free trust, as described above, for the husband's benefit. The new law allows you to give $100,000 to your spouse tax-free (in a lump sum or spread over several years) in addition to $6,000 every year.

If all property is held jointly, the couple loses the tax-saving advantage outlined above. Joint property automatically passes to the other owner when one owner dies, so it's not possible to put part of it away in a tax-saving trust.

In community property states, the higher deduction from estate taxes makes trusts more attractive. With only a $60,000 exemption, as under the old law, a trust often wasn't worth its cost, but now each spouse can shelter up to $175,000 each. There's also a marital deduction adjustment for which you'll probably want to qualify.