On those rare occasions when insurance executive Tara Guizot wears a suit to her Los Angeles office, "people invariably ask me if I'm interviewing for a new job," she said.

The trend toward casual dress has gone so far that Matt Smith, a 27-year-old Los Angeles lawyer, is on a quest to establish "Tie Tuesday." He would like to wear a suit to work but knows he'd be ridiculed. Instead, Smith dons a tie every Tuesday and hopes other men in his office will follow. So far a couple have. "It's just something fun," he said.

Forget casual Fridays. In many workplaces, it's casual everyday as corporate dress codes have gone the way of fedoras and white gloves.

Office workers, from executives to receptionists, now wear pretty much what they want, sometimes baring more cleavage, tattoos and body fat than co-workers care to see.

The sartorial style pioneered by the T-shirt-and-jeans-wearing technology moguls of Silicon Valley more than a decade ago has spread even to law offices, accounting firms and corporate headquarters — bastions of tradition that had kept generations of Brooks Brothers salesmen busy teaching customers how to fold silk pocket squares.

Polo shirts, sweater sets and tailored slacks — what many companies consider "business casual" — have given way to halter tops, rubber slippers, T-shirts and jeans.

The trend has even sparked a mini-backlash among professionals opting for a more buttoned-down look.

"Wearing a tie used to be a sign of conformity. But dressing down is now conformity, and dressing up is rebellious," said Robert Stephens, who founded the Geek Squad, Best Buy Co.'s computer repair service. Squad members sport short-sleeve white shirts and black ties.

Credit younger workers, who bring a who-cares-what-I-wear attitude to their cubicles, for the casual-everyday trend. The hip-hugging jeans and silk-screened tees they favor have caught on with aging baby boomers, many of whom started their careers with a closet full of pinstriped "power" suits. Many women believe they no longer need to look suited-up like men to be taken seriously in the office.

Today's casual dress also reflects the needs of parents who want to be comfortable as they race from staff meetings to their kids' soccer practices.

Employers who once took a hard line on suits and pantyhose realized they risked losing valued staff members unless they lightened up.

"It really helps us, specifically with Gen X and Y workers," said Miriam Wardak, senior vice president for ICF International, a Virginia-based consulting firm, adding that some younger workers have told her they would not consider a potential employer if they had to wear a suit and tie.

But today's lax dress codes are raising tough questions for managers about what's acceptably casual and what's too sloppy, offensive or revealing.

Victoria Johnson said she never bought into business casual. "To me it means business sloppy," said the 47-year-old, who heads her own Los Angeles-based management consulting firm.

Attired in a navy straight skirt, matching jacket, heels and yes, pantyhose, Johnson said she believes "your appearance is your calling card; it speaks before you open your mouth."

Most companies have dress codes, whether formal or informal. "Companies want neat and clean, a notch above what you might wear at home," said John Challenger, who heads outplacement firm Challenger, Gray & Christmas Inc. But some workplaces seem to have abandoned hope of even that.

Packaged food giant General Mills Inc., which had formal rules until the mid-1990s, now simply asks employees to "dress for your day," spokeswoman Kirstie Foster said. The company suggests that "traditional business attire may be more appropriate on days when employees have meetings scheduled with customers or external clients."

Generational shifts also explain the move to casual.

Baby boomers "felt compelled to express themselves through work and to be winners in that arena," said Peter Rose, a partner with the marketing research firm Yankelovich Inc. The mannish dress-for-success suits with floppy bows many young women wore in the early 1980s were testament to that ambition, he said.

But as Gen-Xers entered the work force in the late 1980s, "they didn't feel as compelled to exhibit that sense of 'I have to be a winner,' " Rose said, even though many are just as driven.

Gen-Yers, also called echo boomers — roughly those between 18 and 26 years old — have an "even more relaxed set of standards, and they especially don't like to be told what to do," Rose said. A bare midriff or cargo pants may look sloppy to a baby boomer, he said, "but to an echo it says, 'I need to be comfortable.' " An echo boomer "thinks nothing of wearing a nose ring to an interview," while boomers or Gen-Xers "would think you're out of your mind," Rose said.

At 29, Olga Shmuklyer, a New York public relations consultant, straddles the line between Gen X and Gen Y. "My generation just wants to be comfortable in our work," she said, "but I can see how older people might look at us and think we're too casual."

The same goes for older workers juggling kids, ailing parents and their own leisure activities.

"People are so busy now," said Marshal Cohen, chief analyst at NPD Group, a marketing information company. "They're more and more into a universal product, something they can wear to work and to the gym.

"No one goes home between each activity anymore; they don't have the time," he said.

The fashion industry has capitalized on the casual shift in wardrobe tastes, Cohen said, with $250 jeans and $300 jeweled flip-flops.

Yet even some designers profiting from the trend are surprised by how casually employees dress these days.

"When I was in college working at Marshall Field's, you couldn't wear open-toed shoes, and you always had to wear hose, no matter how sweltering the summer," recalled Anne Cashill, director of corporate merchandising and design at Liz Claiborne Inc. Now she sees "things I'd never dream of wearing to work," including a woman on her floor who recently wore a bra-less halter top.

"We're contributors to this situation," Cashill admitted. The New York-based company owns the ultra-casual Juicy Couture and Lucky Brand Jeans lines. "For many of our businesses, it's a very good thing," she said of the casual trend.

The popularity of casual shoes has stomped out one of the last office dress no-no's — bare toes.

Guizot, an insurance company vice president, said her workplace lifted that ban about a year ago. Employees are still asked not to wear rubber slippers, she said, "but many do."

However, supervisors at other companies recount awkward conversations when employees cross the line.

At Merit Cos., employees whose attire violates the firm's written dress code are sometimes sent home to change.

Most recognize their slip-up and take the gentle reprimand in stride, said Angela Genaro, human resources director at the Aliso Viejo, Calif.-based property management firm.

"It always surprises me when an employee says, 'Oh, when I got dressed this morning, I thought this might be questionable,' " she said.

The slide toward weekend clothing has now sparked a bit of a countertrend, said Cohen.

Boomers especially are dressing up, he said, trying to "separate themselves from younger generations." So are ambitious junior professionals.

The reversal is most evident among men. Sales of men's tailored clothing totaled $5.1 billion during the 12 months ended in May, compared with $4.6 billion in the previous year, according to NPD. Sales of women's tailored items have been flat.