Retired people across the country will find it easier to get the financing they need to change their living arrangements under new policies recently announced by a major secondary mortgage lender.

The idea is to allow anyone 62 or older more options in housing than they have now, including:- Building a separate-quarters addition to an existing house for added income. (Or perhaps an adult might want to build such an addition for an elderly parent to live in.)

- Building a stand-alone cottage on your property for a relative.

- Sharing your home with others for added income, or buying a house jointly with an unrelated person. The new program makes this more financially attractive than it has been in the past.

- Selling your house but continuing to live in it as a renter. This is already possible, but the new program makes it easier to arrange.

The company behind these ideas is the Federal National Mortgage Association, known as Fannie Mae. It buys mortgages from local lenders - 4,000 of them nationwide - and sets standards that the lenders must follow if they want to sell their loans to Fannie Mae.

Because of that arrangement, whenever Fannie Mae announces a new program, it's likely you will be able to find a lender in your community willing to make loans that meet Fannie Mae's criteria.

Fannie Mae calls its latest program SHO, for Seniors' Housing Opportunities. It offers these examples of financing an elderly person can get:

Jane owns a house worth $50,000, with a mortgage of $25,000. She needs more income and wants to build an attached apartment to her house that she can rent out for $200 a month.

Under Fannie Mae's new guidelines, Jane can refinance and get a mortgage for up to 90 percent of the value of her house - in this case, $45,000. After she pays off her $25,000 mortgage, she will have $20,000 left to build the addition.

Jane needs an annual income of $18,400 to qualify for her new $45,000 mortgage, but since she can count the $200 a month she will receive by renting out the apartment, she needs only $16,000 in other income.

Even if Jane can't meet the income qualifications, she still might get the loan, depending on how much she has in savings and investments, her track record on mortgage payments, and whether her other monthly expenses are low.

Jane also could buy a house that has an apartment attached. In that case, she could get a mortgage for up to 95 percent of the value of the house.

Or Jane could use these same arrangements to build a cottage on her property but not attached to her house. She could have an efficiency apartment built for less tha $20,000.

Jane has several other options.

If she wanted to buy a $50,000 house and share it with three other people, each paying her $200 a month rent, she could get a $45,000 mortgage with an income of just $11,200 a year because Fannie Mae will allow her to count the rent from her boarders as income.

Finally, Jane might want to sell her house to her daughter and lease it back. Under Fannie Mae's new standards, when an elderly person is the tenant the investor can get a mortgage for 90 percent of the property value.

Jane also could sell her house to a non-profit agency and get the same benefits.

You also can get more information about the programs by writing to Fannie Mae, P.O. Drawer SHO, 3900 Wisconsin Ave., Washington, DC 20016.