The new year that begins today ushers in a raft of new laws and regulations that are a mixed blessing: Social Security recipients and members of the armed forces will receive an increase in benefits, some federal judges will get a pay raise, and jockeys at Maryland race tracks will at long last qualify for workmen's compensation payments for job-related injuries.

But 1986 is off to a less auspicious start for District consumers, who will have to pay a nickel more to make a call from a telephone booth, for anyone who owns an old, leaded-gasoline-guzzling car, and for the hapless Capitol Hill aide who mistakenly left out a key page of a bill bound for the White House that would aid D.C. universities.

The mix-up in transmitting the bill has jeopardized the issuance of $64 million worth of tax-exempt revenue bonds for George Washington University and American University, although city officials hope to rectify the error when Congress reconvenes this month.

"It was a really freak mistake," said Cindy Gist, a D.C. City Council staff member who said the second page of the legislation, which waived the 30-day congressional review period for District measures, was left off the bill when it was sent from Congress to the White House for President Reagan's signature.

The District was rushing to exempt George Washington, American and Georgetown universities from a $200 million cap imposed on the city's issuance of tax exempt revenue bonds under a new tax reform bill that has been passed in the House and is awaiting action in the Senate. The waiver for Georgetown survived on another page of the bill, which the president signed, but the city will have to go back to Congress to get the waiver for George Washington and American universities.

There will be no going back to Congress, however, on another measure that will affect District residents.

Starting today, the cost of local calls placed from pay phones will rise from 15 cents to 20 cents. Similar calls are 25 cents in Virginia and Maryland.

The pay phone toll is part of an overall increase in the cost of basic telephone services in the District. Under a new rate plan approved by the D.C. Public Service Commission, costs will rise by as much as 50 percent for residential customers and by up to 63 percent for business customers.

In Maryland, the jockeys, who number about 75, weren't the only ones to benefit from state laws that take effect today. The most visible new statute is one that permits motorists to apply for vanity license plates with seven letters or digits instead of six. The new, more expressive tags will cost $25.

Another new Maryland measure will give the public greater access to records on industrial plants that produce toxic wastes. The law applies to state residents who live near such plants and want to see routine health department reports about them.

On the national front, changes in federal law today will give a 3.1 percent cost-of-living increase to millions of people who receive government Social Security checks. In addition, President Reagan signed an executive order yesterday that implements a retroactive pay increase back to last January for some federal judges and gives members of the armed forces a 3 percent pay raise.

The average Social Security recipient making $464 a month will get a $14 increase in 1986; the average couple will get $812 a month instead of $788. The maximum individual check rises from $717 to $739 for someone age 65 retiring this year. There are 37 million Social Security recipients nationwide.

But what Uncle Sam gives with one hand, he often takes away with the other: It will cost more to finance Social Security, and the Social Security payroll tax went up at midnight from 7.05 to 7.15 percent.

Today also marks the beginning of the end for leaded gasoline -- and the end of bargain fuel prices for 40 million motorists. Under a new federal law, the amount of lead in gasoline will be sharply reduced, from 0.5 grams per gallon to 0.1 gram. The change to virtually lead-free gas will mean higher fuel costs for owners of leaded-gas vehicles, mostly pre-1975 models, which still constitute 26.5 percent of the nation's 155 million cars and trucks.