At the Massey Building governmental headquarters and elsewhere in Fairfax County, clocks registered 3 o'clock. But the hands of the clock in the steeple of Fairfax City Hall stood at 2 o'clock.

Was the city, again, asserting its independence? No, someone simply hadn't gotten around to putting the clock hands ahead since daylight saving time went into effect last month.

Inside the city hall, however, independence is as strong as ever. In fact, city officials are circulating a white paper comparing the city and county governments, and concluding that the city is more efficient and equitable and puts less of a tax burden on residents.

Was it significant that the white paper was being circulated in the midst of city-county talks on renegotiating contracts under which the county supplies the city with various services, such as schooling and sewage treatment?

"Oh, no," assistant city manager Robert C. Norris said. "We just decided to put together these different comparisons."

The most stinging comparisons is of assessment practices. Norris says in the white paper that ". . . the city's program is far superior to the county's and, as such, is more equitable in the treatment of different classes of property owners."

To back up that claim, city assessment director R. Douglas Sensabaugh analyzed assessments in Mosby Woods, a subdivision that straddles the city-county boundary. He found that his office's assessments of houses on the city's side of Mosby Woods were within 99 per cent of market price. The county's assessments, he said, only came within 86 per cent of market price.

At the Massey Building, Samuel A. Patteson Jr., supervisor of the county assessment office, is not inclined to be drawn into a conversial comparison with the city.

"We don't compare ourselves to Fairfax City," Patteson said. "We compare ourselves to bigger jurisdictions."

What about the differences in assessments in Mosby Woods? Patteson's answer is that if the city has a median sales assessment ratio of 99 per cent, then it must be assessing some houses at more than 100 per cent. An assessment of more than 100 per cent of fair market price would violate state law.

The city's Sensabaugh challenges anybody to find an assessment made by his office that exceeds fair market value.

"Our record is the best in the state," Sensabaugh said. Then, in an impact challenge to Patteson, he added: "if we can do it, anybody can do it."

The comparison of assessment practices is being made when, for the second time, the county is being sued by an organization called the Taxpayers Alliance for allegedly unfair assessments. The first suit was won by the county in circuit court, and an appeal was dismissed by the State Supreme Court on a technicality.

Fairfax City's higher accuracy in assessing means that city residents in Mosby Woods pay higher real estate taxes than county residents of the subdivision. But Dale Lestina says that he and other residents of the county plan to file a suit this summer calling for the annexation of their property by the city. Lestina, who heads the annexation committee of the Mosby Woods Community Association, says union with the city is favored "by almost 90 percent" on the county side.

Lestina says that subdivision residents on the city side do not, ultimately, pay more taxes, even though their houses are assessed at virtually market price. The reasons: The county tax rate is 1 cent higher ($1.74 vs. the city's $1.73), the county charges extra for trash picj kup ($76), a service included in city taxes, some county areas are taxed 3 or 4 cents additionally to pay for community centers serving them; and the county's personal property tax is higher.

Actually, the owner of a $58,000 house on the county side of Mosby Woods would end up paying about $27 more annually than a city resident of Mosby Woods. The estimate assumes the county-side house is assessed at 86 per cent, while the sity-side house is assessed at 99 per cent. It also assumes that both residents owned a 1975 Chevelle Malibu, and that the county residsents paid $76 extra for trash pickup and 3 cents more on his tax rate for a community center.

The Fairfax City white paper says the city has a substantially lower effective real and personal property tax rate than the county. That's true, but if the city is assessing houses closer to market value than the county, city residents may not benefit from a tax rate that is "effectively" lower.

County officials declined to comment on the claims made in the city white paper. They view the document as a political ploy designed to influence talks on county-supplied city services. (In the paper, the city says it is already paying the county more for sewage treatment than the county is charging its own residents.)