District of Columbia City Council members took their first official look at Mayor Walter E. Washington's proposed $1.4 billion 1979 budget yesterday, and they immediately questioned some of the ways the mayor plans to support the budget.

Members also were perturbed that the budget was released to the news media before the Council saw it.

Some Council members were disappointed because the budget would grant a one-year delay of a plan to accelerate tax payments for large businesses in order to avoid "cash flow" problems for the firms.

Others questioned the mayor's assertion that the budget, which includes no increase in the city's property tax rate, is a "no tax-increase budget." The budget assumes an average increase of 23 per cent in the assessed value of homes and businesses in the city during the next two years.

"The budget is technically not a tax increase budget," said Marion Barry (D-at large,) chairman of the Council's finance and revenue committee. "But in 1979, we are going to experience at least a 15 per cent increase in assessments. I suspect it will be higher. There is not room at this point for any (property tax) relief.

"You are saying no tax increase," Wilhelmina J. Rolard (D-eight) told budget director Comer S. Coppie. "I can't understand that, because some of the things you are talking about in there sound like taxes to me."

Douglas E. Moore (D-at large) refused to believe Coppice. "That's garbage, that is incredibile," Moore said.

Yesterday's session marked the beginning of the two-month long battle between the mayor and the Council about the city's plans to raise and spend money for the fiscal year beginning Oct. 1, 1978.

The budget battle, like the preparation of the document unveiled Monday by the mayor, is taking place in an atmosphere of uncertainty. The 1979 budget is premised on the 1978 budget proposal that still is pending before Congress, which has final authority on city government spending.

The mayor's proposed 1979 budget includes $1.313 million for operation expenses and another $129 million for capital programs.It is $76 million - or 6.2 per cent - more than the $1.4 billion budget proposed for FY 1978, which begins next month.

A shift of tax payment dates for about 150 firms that pay more than $100,000 per year in property tax is part of a plan to balance the budget. The shift would produced an additional $15 million in revenue.

The same payment date change was planned as a way to help balance the 1978 budget but was abandoned when city finance officials discovered that they were taking in more money than originally projected and when large businesses complained that a one-time payment instead of the current two-a-year would create difficulties.

Council members argued yesterday that since some of the previously unexpected revenue was coming from nonbusinessmen, those persons also should receive similar relief in the 1979 budget.

Barry also said that the budget may not be accurate because of conflicting estimates from various city agencies on how much money each agency will have to pay during the year for orders made previously.

"If we put those in our plan as valid obligations and they are not valid, then the whole financial plan is not valid, Barry said.

"That is a problem. But we would see it more as a challenge" to coordinate the estimates, Coppie said.

"It's a challenge to you, Mr. Coppie. But it's a problem to me," Barry responded.

Barry first raised concern that members of the news media were given copies of the budget last Saturday in order to study it prior to the official release Monday while Council members did not receive their copies until Monday.

"That's disrespectful. The press room was full of people with fat books. They knew more about it than anyone on the Council," Barry said, adding that he plans to introduce an amendment to this year's budget act to require that the Council receive the budget first.