Come Monday, residents in three Bay Area counties and 16 cities will have to dig deeper into their pockets to pay some of the highest sales taxes in the state.

San Mateo County will join Alameda and Los Angeles counties with the loftiest countywide sales tax at 9 percent. Shelling out California's second-highest countywide sales tax will be shoppers in Santa Clara County, paying an 8.75 percent rate that mirrors San Francisco County, while Marin County will move up to 8.5 percent.

A trio of cities in Los Angeles County already have reached the 10 percent mark, and Moraga, Half Moon Bay and Albany will come perilously close at 9.5 percent.

"Ouch," said Mountain View resident Cody Valerio of the eighth-cent sales tax increase in Santa Clara County, which was approved -- like most of the other Bay Area increases -- by voters in November. The 10-year tax will raise about $50 million annually for Santa Clara Valley Medical Center and county public health and welfare programs.

County officials say Measure A will cost each of its 604,204 households about $41 a year, with that same amount coming from shoppers visiting from elsewhere.

Backed by the county Board of Supervisors, labor unions and nonprofits who argued it was a modest request to bolster health and safety programs after years of budget cutbacks, the tax also had critics who said the money would be wasted on overly generous government retirement packages.

Valerio voted against the tax because she doesn't believe in funding social services through a flat tax. She'd rather support those services through her private donations.

"No matter how much we increase it, it's never enough," Valerio said of new taxes. Besides, she added, "Didn't we just have a tax hike in January?"

She's right. The local taxes come on top of a quarter-cent, statewide sales tax increase, authorized when California voters backed Proposition 30 in November. Prop 30 is expected to generate an additional $6 billion a year through the new sales tax as well as an income tax increase for those making $250,000 or more a year. The sales tax hike took effect Jan. 1 and will help will fund schools, community colleges and public safety services.

For retired preschool director Marilyn Drino, both taxes are worth paying, particularly the Santa Clara County tax.

"None of us wants our taxes to go up, but we also want to take care of those who cannot take care of themselves," said Drino.

Jon Coupal, president of the Howard Jarvis Taxpayers Association, which regularly opposes tax hikes, is amused by the April Fool's Day timing of the new taxes.

"Actually, it's a lot of fooling" of state taxpayers, he said, adding that he can see no end in sight to the number of taxes -- including a new statewide gas tax that goes into effect in July and will be the highest in the nation -- "until voters start electing more responsible representatives."

Since 1974, local sales taxes can go into effect no sooner than 110 days after their passage, according to state law, but only on the first day of a calendar year quarter: Jan. 1, April 1, July 1 or Oct. 1.

In Santa Clara County, while the extra sales tax will be collected, it can't be spent by the county until litigation over Measure A is resolved. The same local taxpayers' group that fought unsuccessfully last summer to keep the measure off the ballot filed an appeal after it passed to stop it from being enacted.

Lawyers for the Silicon Valley Taxpayers Association argue the measure should not have been on the November ballot because voters weren't deciding any contested county supervisor races, which they say the law requires. All three county supervisor races were decided in the June primary. It's essentially the same case they lost before a Santa Clara County judge late last summer.

A clerk at the court of appeal said an oral argument has not yet been scheduled for the case, and attorneys on both sides still don't know when it will be heard.

Voters in San Mateo County and the city of Half Moon Bay approved measures that will bring in about $60 million a year for the county and $875,000 for Half Moon Bay.

But Charise McHugh, president of the Half Moon Bay Coastside Chamber of Commerce, said she isn't worried the tax will be a drag on the local economy.

"We are a destination with unique and fabulous shops and unbelievable restaurants," McHugh said. "I don't think a few cents more on sales tax will be a deterrent to visit or shop in our town."

Likewise, in the East Bay city of Moraga, where the sales tax is growing from 8.5 percent to 9.5 percent, Linda York, 67, said she didn't remember voting for Measure K, which will raise proceeds for road and infrastructure repairs.

But the longtime Moraga resident said she supports helping the community locally. "If we want services, we need to pay taxes," she said.

Staff writers Aaron Kinney and Jennifer Modenessi contributed to this report. Contact Tracy Seipel at 408-275-0140.

NEW SALES TAXES
In California, 24 cities and three counties will start collecting new sales taxes today.
Here's where they'll be increased around the Bay Area and what the new sales tax rate will be:
Albany: 9.5 percent
Capitola: 8.75 percent
Carmel: 8.5 percent
Fairfield: 8.625 percent
Healdsburg: 8.75 percent
Moraga: 9.5 percent
Orinda: 9 percent
Rio Vista: 8.375 percent
Sebastopol: 9 percent
Vacaville: 7.875 percent
MARIN COUNTY: 8.5 percent
Fairfax: 9 percent
Novato: 9 percent
San Rafael: 9 percent
SAN MATEO COUNTY: 9 percent
Half Moon Bay: 9.5 percent
San Mateo: 9.25 percent
SANTA CLARA COUNTY: 8.75 percent
Campbell: 9 percent
Source: State Board of Equalization