During the past five weeks we've examined the Economic Recovery Tax Act of 1981 and the major changes it wrought for individual taxpayers.

The message is pretty clear: Jane and Joe Average will pay less taxes in the future. This should permit the accumulation of more assets during a lifetime, and at death, those assets are not likely to be diminished by estate taxes before going to heirs.

That's good news for the long term, but how about right now? What tax strategies are advisable between now and the end of the year to take maximum advantage of all the changes?

Before we get specific on ways to reduce your tax bill, I remind you that these suggestions apply only if you expect your financial situation to be about the same next year as it is in 1981.

If you anticipate major changes in income (a promotion, a job change, a spouse going to work) or in tax-related expenses (like buying a house), then you will have to evaluate these comments in terms of the impact of your changing circumstances.

Given the same situation, your federal income tax for 1981 will be slightly lower than what it was for 1980. But 1982 will bring a further reduction, about 9 percent below your 1981 bill.

So it makes sense to defer income if possible to 1982. A salaried employe generally can do little to accomplish this. But if you're self-employed, it would pay to defer December billing until late in the month so that payments don't come in until 1982.

This is true of taking capital gains. A gain taken in 1982 will cost you less in tax dollars than a 1981 transaction. Conversely, a capital loss will be worth more this year than next.

But don't let the opportunity for a tax saving cloud your investment judgment. Tax impact should not be the primary consideration when making buy-sell investment decisions.

For people who itemize deductions, the 1982 tax reduction means that you should move deductions up into 1981 if possible. This won't work for interest (car loan payments, for example); prepaid interest can't be deducted until the year in which it is due.

You can legally move into this year anticipated medical bills like prepayments on a monthly orthodontic payment schedule. Be understanding; your doctor is subject to the same tax laws as you are, and may be rather underwhelmed by your generosity.

You can also move into 1981 some charitable contributions like redeeming a building fund pledge to your church. Since these are tax-exempt institutions, they should be delighted to receive early payments.

If you make quarterly, estimated state tax payments, pay the Jan. 15 installment in late December so you can take the deduction in your 1981 federal return. And if you pay real estate property taxes yourself (rather than having them paid by the mortgage-holder), you may be able to move next year's first-half payment into 1981.

Be careful to weigh the alternatives carefully, however. If you have to borrow money to make a prepayment, the interest may cost more than you save in taxes, even though you can deduct the interest next year.

If you don't expect to itemize deductions in 1981, try to defer until 1982 payments that would qualify for itemizing. Such payments would provide no tax benefit this year; but changing circumstances in 1982 might make itemizing attractive, so it pays to hold potential deductions.

This is particularly true of contributions to charity, because starting in 1982 there will be a small deduction (increasing in later years) for such contributions even for taxpayers who do not itemize deductions.

Of course if you regularly make charitable contributions, you'll probably hit the $100 ceiling next year anyway. (The deduction itself will be limited to 25 percent of that $100.) But hold up anyway, on the chance that you might itemize in 1982.