Q: I've been offered a tax shelter, a limited partnership investment in a proposed office-hotel-casino complex in Reno. I've been assured I can get a 5-to-1 write-off. The minimum investment is $25,000. How can I be sure I'm getting into a viable situation?

A: You can't. virtually every investment carries risks. You can minimize your risks. Here are my suggestions for doing this.

First, carefully check the track record of the people offering the tax shelter investment. How many other tax shelter investments have they done? What was the result in each? Are they considered honest, reliable, competent? Contact limited partners in other tax shelter investments to get this information.

Second, get your attorney to check on the experience and reputation of any attorneys involved. Are the attorneys experienced in real estate transactions generally and tax shelter investments specifically? Do they have a reputaion for intergrity and ability?

Third, ask your accountant to get the same information on the accountants involved in the tax shelter investment.

Two things make me look at this investment with particular care.

First, why do the syndicators come East for this money? If this is a top flight investment, they ought to be able to find money closer to Nevada.

Second, the 5-to-1 write-off (deducting five timed as much for expenses as the cash investment) indicates to me the investment is not particularly good. Tax deductions should be a desirable plus for an investment, not the substance of it.

Here's one final word that may help you in making your decision. If most of your income is salary, a tax shelter investment may not be worth any risk. Your earned income is a subject to a 50 percent maximum tax. A tax shelter just defers paying taxes. Some time you or your heirs are going to have to pay the deffered taxes. That could be at a higher rate than 50 percent.

Moreover, if the limited partnership sells the property and you have a long-term capital gain, the effective tax rate is 49 percent - only 1 percent maximum tax rate.

Q: With so much of each mortgage payment going into the interest column, wouldn't it be better if the homeowner has the money and has lived in his house 10 to 12 years, to pay off the remainder of the mortgage, rather than continuing all that interest for some eight to 20 years?

A: It depends on whether you can earn a greater return on your money than you are paying in interest on your mortgage debt. Here's what I mean. Suppose your mortgage interest rate is eight percent and you invest current money in sound investments to return you 10 percent. Are you better off to invest your money than to pay off your mortgage debt? Consider also that you're paying off the mortgage with "cheaper" money in an inflationary economy.

True, you have to pay income tax on your 10 percent return. But the interest portion of your mortgage debt is deductible in computing your income tax.

There's one intangble I haven't considered. Some people want a mortgage-free home even if it costs tham a little money. If that's your desire, then by all means use your excess cash to pay off your mortgage. And, of course, if the rate of return on current money is less than the interest rate on your mortgage debt, then it's logical to use your excess cash to pay off your mortgage.