About 10 years ago my daughter and son-in-law moved to Brussels, Belgium, for an extended stay. They took some cash with them in the form of traveler's checks, and arranged for my son-in-law's brother to maintain their U.S. bank account, pay some bills and forward funds to them from time to time.

There were the inevitable emergencies, often compounded by misunderstandings and the hazards of overseas telephone circuits, until they finally were settled in Belgium and were able to get their finances organized with a local Belgian bank.

Now there seems to be a better way. I recently got a package of informational material from Citicorp describing a new family of banking services designed specifically for Americans living and working abroad.

The family of services is called "Personal Banking for Overseas Americans." It includes a wide range of personal financial services geared primarily for high-salaried American executives who live in other countries but still have some financial responsibilities in the United States.

The package is built around a personal banker at Citibank who handles your banking needs and is familiar with your particular circumstances. He, or she, responds to your instructions or queries by telephone during normal U.S. office hours.

This may not be convenient in an area with a major difference in time zones--the whole world is not on Eastern Standard Time--so a 24-hour telex is available. Your overnight telex to Citibank will get action the next business day, including a telephone callback from your personal banker if needed. (You pay for your call or telex, Citibank pays for any callback they place.)

You may have your salary deposited directly with Citibank. From your account the bank will forward whatever amount you specify monthly or semimonthly, in dollars or local currency, to your local bank account overseas.

Citibank will also pay specified bills like mortgage and utility payments on a house in the United States, tuition for a child attending an American college or monthly deposits into an IRA investment plan.

At regular intervals, or whenever the account balance reaches a specified level, in response to your telexed instructions, a sum of money can be transferred to a higher-yielding Citibank instrument like a CD or to your broker for other investment plans.

The bill-paying provision may help preserve your credit rating by insuring that bills are paid on time and are not subject to unpredictable travel plans or the uncertainties of overseas postal systems.

Perhaps more important, from a credit point of view, is the maintenance of a financial "presence" in the United States. Americans working abroad for extended periods often find they have become "credit non-entities" in the United States.

Because they have no recent history of U.S. residence and often go for long periods without any credit transactions in the United States, expatriates sometimes find they simply do not appear in the files of the normal credit research organizations.

Subscribers to Personal Banking for Overseas Americans at the very least maintain a financial profile at Citibank and have a major U.S. banking organization to cite as a reference if needed.

Of course this service doesn't come for free. Citibank has two fee schedules, for $29 a month you get all the services and up to four scheduled payments each month plus up to four cable (phone or telex) transactions a year. $42 a month will get you the same personal services plus an unlimited number of prearranged bill payments and special cable transactions. (Citibank says the fee is tax-deductible if you itemize.)

A free booklet offering 20 tips for managing your money from abroad is available by writing to Citibank, Personal Banking for Overseas Americans, 666 Fifth Ave., New York, N.Y. 10103. Included in the booklet is a coupon you can return for further information on the overseas banking program.

I have no connection of any kind with Citicorp/Citibank and this is not a recommendation for their new service. But in this city, information on overseas living is probably important to more people than in any other city in the country.

And this expanded financial service is yet another illustration of a phenomenon I have been talking about in recent weeks--the expanded activities of the various financial institutions and the trend towards the one-stop financial supermarket.