A Baltimore savings and loan company has sent a letter to all of its customers -- including some in the Washington area -- that is being interpreted as a threat to foreclose immediately when a home mortgage payment is late even one day.

One angry recipient, Martin Barmack of Bethesda, called the letter "a scare tactic to get people to pay early."

A lawyer who specializes in real estate cases said the company "may be really pressed for money and holding a lot of old low-interest loans."

Gerald S. Klein, chairman of the firm, Merritt Savings and Loan Inc. of Baltimore, would say only that the letter was intended to remind its customers to pay promptly.

The paragraph that drew the most fire warned "that any time a payment is received after the first of the month, we will be free to exercise our option of requiring the mortgage to be paid in full and at once." The letter was signed by Klein.

The specter of swift foreclosure has been raised at a time of trouble for S&Ls and the housing industry as a result of the continuing recession and high unemployment. Record highs in mortgage delinquencies and the number of home loan foreclosures were reported this month by the Mortgage Bankers Association. The loans on about 1.5 million homes were in default in the second quarter of the year, and about 150,000 homes across the nation were involved in foreclosure proceedings.

Most lenders these days are moving more swiftly than in the past to remedy deliquencies, say lending industry spokesmen, housing counselors, real estate brokers and attorneys. Some believe banks and S&Ls are more likely to press for refinancing or foreclosure proceedings on loans with single-digit interest rates.

All said they have not heard of other lender actions as Draconian as those described in the Merritt letter.

Barmack, whose 8 3/4 percent loan on an Ocean City condominium is held by Merritt, said, "People who are scared by this letter will probably send early payments. If they Merritt can get the money five days ahead, they can collect a lot of interest."

Attorneys and other experts in the field said Merritt theoretically could demand immediate payment in full after one day of delinquency if the contract does not expressly forbid such action. But they said homeowners with records of prompt payment probably could appeal successfully to courts to stop such foreclosure proceedings.

Klein maintained that none of the company's mortgagors "needs to be upset.

"Looking at our mortgages, it was our opinion that our customers needed a reminder. Many . . . took too many days to pay their mortgage payment," he said. The chairman said he and an associate who he refused to identify bought Merritt about six months ago. The company has assets of about $100 million, he said.

Klein refused to discuss the contents of the letter further, except to say, "If you know of any case we have foreclosed upon . . . I'd be happy to discuss it with you."

He said the letter was the first of its kind that Merritt has sent to its customers. That one was enough to stir up a flurry of protest and a subsequent letter expressing the company's "regrets" did little to mollify customers such as Barmack. The Bethesda homeowner noted that the second letter did not back away from the warning in the first one.

Barmack said he plans to mail his mortgage payments on the 20th of each month, well in advance of the due date of the first. But the check's date will be the first of the month, and Barmack plans to enclose a note that it is not to be cashed until that date.

An Annandale homeowner, who said the Baltimore firm bought his 8 1/2 percent mortgage from a Virginia company, called the Merritt letter "threatening" and added, "I was very offended."

He also believes Merritt is trying to pull in early payments from customers, and he isn't happy about it. "They have an escrow account that they're making money on," he fumed. "They pay property taxes twice a year and I have to pay a portion every month."

Older loan contracts often do not have provisions that prevent immediate foreclosures. But mortgage agreement forms used by most lenders since the mid-1970s contain protections for borrowers, said attorney George Ballman, general counsel for the Montgomery County Board of Realtors. These include a 30-day "right to reinstate" during which lenders cannot refuse to accept overdue payments.

Many lenders use forms provided by the Federal Home Loan Mortgage Corp. and the Federal National Morgage Association, which require the lender to accept overdue payments and reasonable legal fees up to five days before a foreclosure sale and to reinstate the mortgage at its original interest rate.

The homeowner protections in these forms are stricter than those in District of Columbia law, said another attorney, Joseph Gervasio. But if the restrictions are not present in a borrower's contract, D.C. law provides that the lender must file papers announcing his intention to foreclose with the city recorder of deeds 30 days before the process begins.

Courts are not involved in a D.C. foreclosure unless the borrower wants to contest it. A homeowner can ask for an injunction, and "it's been my understanding the courts frown on someone foreclosing when there's only a one-month delinquency," said Gervasio, who recommends that a lender wait three months before instituting foreclosure proceedings.

Maryland and Virginia laws do not contain any provisions for grace periods or prohibitions on immediate foreclosures. But attorneys in both states echo Gervasio, saying courts could be expected to react favorably to an appeal for more time from a homeowner with a record of prompt payments.

Industry spokesmen also say that most lenders do not want to take back property that they may have difficulty selling in the present market.

Maryland attorney George Ballman believes that "most reputable banks and S&Ls are not in the foreclosure business and will bend over backward to work with a borrower. If you call and say you're having a bad time with payments, most lenders" will try to be helpful.

There are exceptions, and the experience of Kensington homeowner Jerry Jewell is an example. Last December, Jewell tried to give Maryland Federal Savings and Loan Association a certified check to cover two late mortgage payments and late fees. The S&L refused to accept it and said it planned to foreclose. Jewell turned to a court for help and is still living in his home while he awaits the outcome of his case.