For homeowners having trouble selling their houses in a tight money market, taking back the mortgage can sometimes be the solution.

Holding a mortgage is a bit like eating oysters on the half shell: It is not for everyone. As a mortgage holder you will receive a down payment, but you will not get the lump-sum payment that comes with selling through a conventional lending institution.

Also, your age and financial circumstances must be such that you will benefit from stretching out the payments over many years. In addition, you or your representative should be in the area to keep in touch with the property and the mortgagor.

Assuming that there will be no economic earthquakes in the next several years, with the repeal of usury laws a mortgage can be a reasonably satisfactory source of income. The relatively little risk is secured by property.

If you do decide to hold a mortgage, be sure you have an experienced lawyer or real estate agent draw up the sales contract for an agreed fee, not a commission. Be sure that the contract specifies that it is contingent upon your approval of the purchaser's credit status.

The key to a sound mortgage is an accurate estimate of the fiscal reliability and strength of the prospective buyer. How much is his or her income and where does it come from? What are the buyer's expenses compared to income? How much does he or she owe to whom, and how regularly are bills paid?

The easiest way to get accurate answers to these and related questions is to require that the prospects furnish you with copies of their last three income tax returns, and with the names, addresses and phone numbers of their employers, banks, and firms from which they have borrowed money or with which they do business. A sound prospect will be more than willing to alert those offices to expect your inquiries and to supply the appropriate information.

As soon as you receive the income tax and other data, check them out thoroughly. Make notes on all the information you collect. This information is important not only in deciding whether or not to hold the mortgage of a particular purchaser, but may prove invaluable later on in the life of the mortgage in case any questions or problems arise.

Two systems can be used to handle the payment of real estate taxes. One is to use the system of conventional lending institutions, and have the tax payment included in the monthly payment. In this case the tax money has to be separated into an escrow account.

Another way is to have the mortgagor pay the taxes direct to the government.

The system involving the escrow account is a safe, but complicated, arrangement for a private individual to set up. On the other hand, if it is left up to the mortgagor to pay the taxes, then it is prudent for the mortgage holder to check regularly with the local tax office to be sure that payments are being made.

If the taxes are not being paid promptly, the mortgage holder should remind the mortgagor. If he is unable to pay the taxes before the property is liable to be sold at public auction, then the mortgage holder should be prepared to step in and pay the taxes, and foreclose the mortgage.

As a general rule, in dealing with people who have owned property before, such problems can be forestalled by a careful checking of the propect before sale. However, if a prospect has never owned property nor had experience with paying taxes or water or insurance bills, it is a good idea to review these obligations with him or her at settlement. In addition, a list of these obligations should also be sent to the mortgagor by certified mail shortly after settlement.

While the payment of taxes can be a bit complicated, the collection of the monthly payment of the principal and interest can be simplicity itself.

Many local banks will perform this service for you for a nominal charge, sending you a notice when each payment is received. Although the bank will collect payments and keep track of interest and principal, usually it will not function as a commercial bill collector.

Thus it is up to the prudent mortgage holder to promptly contact a mortgagee who is having trouble paying the note on time. Often a phone call is enough.

If a mortgagor is chronically late in making payments, the mortgage holder can ask the bank to send a written report on the status of the mortgage. A copy of this should be sent to the mortgagor for comment.

If this doesn't work, a face-to-face meeting should be set up within a week. When you call the mortgagor to set up this meeting, remind the mortgagor that, under the provisions of the mortgage, default in the payment of any installment means that you can call for the immediate payment of the full mortgage.