Boston — Commercial banks and many thrift institutions have already become look-alikes. They could soon become something close to identical twins.
Massachusetts may soon hasten this transformation by passing legislation, the first in the nation, that would provide the same legal status and banking powers to state-chartered commercial banks, mutual savings banks, and cooperative banks (the state equivalent of savings-and-loan associations).
The legislature's Committee on Banks and Banking unanimously approved this comprehensive banking legislation at the end of last month. It would by 1986:
1. Give thrifts completely the same banking powers as commercial banks. There would be no ceiling, for instance, on the proportion of their assets that could be invested in commercial loans.
2. Authorize statewide mergers by commercial banks, mutual savings banks, and cooperative banks in any combination. Mutuals and cooperatives could also convert to stock-owned institutions.
3. Over three years, thrifts would convert to the same tax formula as commercial banks.
In other words, all state depository institutions would be playing on a ''level playing field'' - the same law would apply to all of them. Each depository institution could shape its future as it wished, concentrating on mortgages, commercial loans, personal loans, or whatever on the asset side, and free to accept demand deposits, NOW accounts, various savings certificates, issue certificates of deposit, etc., on the liability side.
Should the legislation pass here, it will spread to other states, predicts Elliott G. Carr, president of the Savings Bank Association of Massachusetts. ''Massachusetts has a reputation for being on the cutting edge of legislation,'' he says, recalling how NOW accounts got their start in the state in 1972.
Sen. Jake Garn (R) of Utah has proposed federal banking legislation that would do something similar for federal depository institutions. But because of a split among the various lobbying groups on details, its chances of passage are considered slim this year. The American Bankers Association, for instance, wants commercial banks to obtain greater powers to do business in the real estate and insurance areas if thrifts are to get the expanded powers provided in the legislation.
In Massachusetts, the three major trade groups - the Massachusetts Banking Association (MBA), the Savings Banks Association of Massachusetts, and the Massachusetts Co-operative Bank League - favor the bill.
''Our attitude caught a lot of people by surprise,'' admits Paul J. Foley, president of the MBA, which has 133 members, half of them state-chartered. ''We feel the old Hatfield-McCoy syndrome of the thrifts and banks ought to be dropped.''
One reason is that the commercial bankers decided it was important to them that thrifts remain healthy institutions, and that depository institutions as a group be able to compete with nonbanking entities, such as Merrill Lynch, American Express, Sears, Roebuck, and Fidelity (the expanding mutual fund group) , companies that are increasingly invading the banking field.
Because of this unity among the banking and thrift groups, Mr. Carr, president of the 159-member savings bank group, figures the bill has a ''good chance'' of passing within a couple of months.
Some smaller institutions, however, are reportedly not in agreement with their associations and could raise some trouble for the bill in the legislature.
Will full investment freedom for thrifts mean that the housing market will be more poorly served with mortgages in the future?
Carr argues that this will not be the case. For one thing, he expects thrifts , on average, to move only slowly into commercial lending, the trust business, or other commercial banking areas. ''Most Massachusetts savings banks want to remain savings banks, remain real estate lenders,'' he says.
Second, he figures the thrifts will be in no shape to make many mortgage loans at all unless they are in better financial shape, and that over the long run, greater banking powers could improve their position. Because Massachusetts savings banks have been freer to diversify their assets than most thrifts, they are on average in better condition than most savings institutions in the nations , he maintains.
Nonetheless, some economists might argue that if investment in housing has to compete fully with other investment opportunities, the cost of housing loans would likely remain higher in the future than it was before the 1981-82 run-up in interest rates.
The Massachusetts bill is designed to eliminate any distinctions in the laws governing the state depository institutions by April 1, 1986. That's when Regulation Q - a federal rule governing interest rates - comes to an end. A one-quarter of 1 percent interest rate advantage on savings deposits of the thrifts over commercial banks would then be abolished.
In the interim, Massachusetts thrifts would be allowed greater powers in steps. For instance, thrifts could increase their commercial lending from 5 percent to 10 percent of assets this year. At the moment, federal thrifts have many of the banking powers of commercial banks. But they are limited as to the amount of their assets that can be invested, for instance, in commercial loans. And mergers are permitted with commercial banks only if the thrift is endangered financially.
If, however, state-chartered thrifts get more banking powers, Congress will soon come under pressure to give federal thrifts greater powers. Consumers could soon have a hard time trying to tell a thrift from a commercial bank.