When Minnie Allen's rent was raised to $150 a month in violation of the District of Columbia's controversial rent control law, she concluded that she could no longer afford the costs of her modest apartment on 2d Street NE.

"My total monthly income is: Social Security $102.20 and welfare $85.60," Allen, a small, frail woman with graying hair tied in tiny pigtails, said In a petition to the D.C. Rental Accommodations Office, the agency that runs the rent control program."The $60 increase in rent per month is more than I can pay. I'm 80 years old, not able to work and if this increase becomes effective, I have no alternative but to be evicted."

Hundreds of complaints about excessive rents and other abuses have been lodged with the Rental Accommodations Office by tenants such as Allen during the 3 1/2 years that rent control has been in effect in the city. Many of these allegations, including Allen's, have been found to be valid. Rent rollbacks and refunds, amounting to hundreds of dollars each for many tenants, frequently have been ordered.

How widespread and how serious are these violations of the city's rent control law remains in dispute, with tenants terming them numerous and harmful, while landlords regard them 26 relatively inconsequential.

Some tenant advocates assert that many additional abuses go unobserved, unreported or unremedied, partly because the city government does little to enforce the rent control law. The Rental Accommodations Office takes action on tenants' complaints but does not sek to ferret out unreported abuses. Officials say the agency's staff is too small to try to police the real estate industry.

Some real estate spokesmen argue, nonetheless, that most violations are committed inadvertently by small property owners because of confusion over the complex law. They say that most major real estate companies try to abide by the rent control law and that violations rarely are intentional.

The extent to which the rent control law is violated is part of a broader debate about the system's administration and scope.

Some tenant leaders contend that the law has been further weakened by what they term loopholes that exempt some landlords from its provisions.

Although Allen won a government-ordered rent rollback to $84 a month, her rent soon was raised, once again, to $150 -- its previous level -- by a new landlord who claimed exemption from the law because he owned only four rental apartments. So Allen, at last, moved out.

This exemption -- for landlords who own four or fewer apartments -- is viewed as a frequently abused loop-hole by some tenant groups. But real estate and other officials describe it as a legitimate means of giving a break to small landlords, who find rent control regulations especially burdensome.

Tenant advocates also complain that the city government has taken too few steps to inform tenants of legal protections available to them under the rent control law. Criticism Persists

Many landlords, citing other aspects of the rent control program, assert that the law has proved unworkable, in part because of what they regard as mismanagement and inefficiency in the agency that administers it. There has been continuing evidence in recent months of improvement in the administration of the Rental Accomodations. Office. But criticism of thea gency persists, especially among landlords and lawyers who represent them.

The rent control program, which sets ceilings on rents charged by most of the city's landlords and regulates other rental practices, has been extended to Sept. 30, 1980, in legislation enacted by the city government. and awaiting congressional review. City officials estimate that 150,000 of the city's 180,000 rented apartments and houses fall under rent control regulations. More than 400,000 D.C. residents, over half the city's population, live in rented housing.

Allen, whose encounter with the rent control system exemplifies several issues in the controversy, had lived since the 1960s in a one-bedroom, second-story apartment in a brick row-house at 2009 2d St. NE. An account of her predicament under rent control has been pieced together mainly from records kept by the Rental Accommodations Office and from interviews with two of her friends and the owners of the building where she had lived.

Her petition to the Rental Accommodations Office was trascribed by a friend, Helen Sherbert, a retired travel consultant who lives in Silver Spring. Allen cannot read or write, and her memory and other mental faculties apparently are failing with age. She is thought to be in her 80s, although her birth date is not known.

Another friend, Annie Latham, who is in her late 70s and confined to a wheelchair, helps Allen with cooking and other daily chores, Latham said in an interview. Latham also lived at 2009 2d St NE and moved out, along with Allen, after their rents increased sharply.

For several years, rents had remained low at 2009 2d St. NE. According to a ledger included among the Rental Accommodations Offices's records, Allen's rent had been $75 a month from 1971 until March, 1974, when it was increased to $80. Tenants had to pay their own gas and electricity bills.

Last January, a new owner, Harold J. Turner, bought the building where Allen lived. Turner, who runs a real estate management firm raised Allen's rent to $90 the next month, attributing the increase to rising maintenance and other costs. The rent raise apparently violated the rent control law -- Allen's new rent was slightly higher than permitted -- but neither Allen nor tenants in the building's other three apartments filed a complaint.

Then last March, Allen's rent was increased to $150 a month -- twice what she had paid during the early 1970s and an amount that left her less that $40 a month for gas, electricity, food and other household expenses. Sherbert, Allen's friend, quickly complained to the Rental Accommodation Office in Allen's behalf.

Allen's former landlord, Turner, who is president of H. J. Turner Real Estate Co., said in a telephone interview that he had raised the rent because he was losing money on the 2d Street NE building and because he mistakenly believed at the time that it was exempt from rent control regulations. An Exemption

A landlord who owns a building with four or fewer apartments is exempt from rent control if he owns no other rental property in the city. Turner acknowledged that he had owned two other structures including five rental apartments but said he had misunderstood the exemption provision and believed incorrectly that it applied to any building with four or fewer apartments irrespective of an owner's other property holdings.

In Allen's petition to the Rental Accommodations Office, another complaint also was mentioned. "The apartment is really not safe," the petition said, "because to use the oven on the gas stove you have to hold it shut with a large piece of wood. The refrigerator drips water from the freezing compartment down into where food is stored. (The apartment) was not properly heated this winter, and (tenants) oftern have no hot water."

Landlords are forbidden to raise rents under rent control if substantial violations of the city's housing code exist in their buildings. Whether code violations existed in Allen's apartment apparently was not determined in the rent control agency's proceedings.

In a decision issued June 30, the Rental Accommodations Office found Allen's rent excessive. It ordered that her cent be reduced to $84 a month to comply with a formula that allowed initial rent increases of 12.32 per cent over the amount charged in February, 1973. It also required that she be given a refund of $352.65 for excessive rent payments since February, 1976, plus 5 1/4 per cent annual interest on the overcharges. Turner paid the refund. Some Got Refunds

Turner, in fact, appears to have done more than was strictly required under the rent control agency's order, by providing similar refunds to other tenants in the building. Latham said she received a refund. One other tenant denied in an interview that she had received a refund, but Turner disputed her statement, saying she had endorsed her refund check back to him because she owed overdue rent payments. The fourth tenant refused to be interviewed. Turner said she also received a refund.

Some tenant advocates complain that the Rental Accommodations Office often fails to investigate whether other tenants in a building are due refunds when one tenant's rent is found excessive. City officials say that, while they sometimes order refunds for all tenants in a building, the rent control agency's staff is too small to initiate investigations that go beyond the scope of evidence presented in formal tenant complaints and proceedings.

While the Rental Accommodations Office was considering Allen's petition, her landlord already was seeking to sell the building. Turner said he tried to find a purchaser who owned no other rental property in the city and therefore would be exempt from rent control. Such a buyer could charge. high enough rents, Turner said. to avoid short-term losses on the building, while hoping for a long-term profit.

On June 16, even before the rent control agency's decision was issued, Turner sold 2009 2d St. NE to a man he described as an acquaintance, Robert T. Morris, a personnel officer for the Federal National Mortgage Association. According to public records, Turner's selling price was $30,000 -- $11,000 more than he paid for the rowhouse a year and a half earlier. Turner's company still manages the building.

Morris quickly raised rents -- first to $150 a month and recently to $167.50. Allen and her friend, Latham, who had lived in the building's other second-story apartment, soon moved out. Both said they could not afford the increases. Latham's income, like Allen's, consists of Social Security and public assistance payments -- a total of $192 a month, she said.

Morris, who bought the row house as a long-term investment, said in a telephone interview that he already has made improvements. But even at the higher rents, he added, he is only breaking even.

Morris apparently is exempt from rent control regulations because, he said, he owns no other rental apartments. Nevertheless, he failed to file an exemption statement with the Rental Accommodations Office. Officials say that failure to file such a claim is a violation of rent control regulations but that penalties for this violations are unlikely under present policy. A Brighter Note

For Allen and Latham, their bewildering encounter with rent control has ended on a brighter note. Both moved in August, with the help of friends and relatives, to cheerful, neat apartments in a modern, federally subsidized building for the elderly and the disabled, known as Fort Lincoln Senior Village, a part of the Fort Lincoln New Town development on bladensburg Road NE. Allen's rent, according to her friend Sherbert, is only $29 a month. Latham said her own rent is $30.

"I just love it here. I like the people and all of them are so nice to me," Allen remarked during an interview at her apartment one day last month.

Allen's complaint to the Rental Accommodations Office was one of more than 1,400 tenant petitions logged by the agency during the two years ending last November, according to the office's most recent statistics. How many of these petitions allege excessive rents is unknown, although such findings appear to be frequent. Among 98 recent decisions on tenant complaints examined by The Washington Post, the agency's hearing examiners concluded in 26 instances that excessive rents had been charged.

Other frequent violations of the city's broad rent control statute range from illegal evictions to failure to reduce rents because of cutbacks in maintenance and services. Many procedural violations also appear to occur, including failures to register apartment buildings with the rent control agency and to give tenants adequate notice to justify rent increases.

Other abuses of the rent control system clearly occur and are not reported to the Rental Accommodations Office. Some real estate specialists, tenant advocates and city officials believe that such violations most often take place in small buildings occupied by low-income tenants, who are least likely to understand or take advantage of protections provided by the rent control law.

Whether such abuses cause serious harm to low-income tenants is subject to some dispute. Some Not Registered

One real estate investor acknowledged in an interview that he knows of buildings, including some he owns, that have not been registered with the rent control agency, and he conceded that rents charged at these buildings may not adhere strictly to rent control regulations. But he argued that rent gouging rarely occurs, even at rich unregistered buildings because landlords have little hope of collecting high rents from low-income tenants. Tenant advocates dispute such contentions.

The real estate investor, who asked not to be identified, added, moreover, that property owners most often disregard the rent control law. They do so not out of greed, he said, but because of what he termed the mind-boggling difficulties of complying with registration and other procedural requirements of the complex law, particularly when dealing with buildings in low-income neighborhoods where record keeping traditionally has been haphazard.

Although landlords who flout the rent control law may face criminal penalties, only three violators within the past 16 months have been referred to the D.C. Corporation Counsel's office for possible prosecution, according to city officials, and no landlord has been convicted in court of rent control abuse.

Some tenant advocates contend that the infrequency of such criminal proceedings is a further reflection of what they regard as lax enforcement of the rent control law. "Numbers of landlords have chosen to ignore the law and assume they can get by with that." Marie Nahikian, a tenant representative on the Rental Accommodations Commission, the board that oversees the rent control agency, complained in an interview.

Other officials argue that most rent control violations stem from inadvertent errors, rather than intentional wrongdoing, and that criminal prosecution in such instances would be unwarranted.