When her father had a major stroke and San Francisco resident Mary Graves needed to take about three weeks off from her job at accounting giant KPMG several months ago, the numbers just didn’t add up. Graves had already finished up her five weeks of paid time off for the fiscal year, so it appeared she would have to be without pay for those three weeks — combining financial stress with her emotional strain.

Then her co-workers stepped in — and stepped up.

Under a program that the tax and advisory firm had established for its workers five years ago, Graves’ colleagues in the San Francisco office were able to donate their own paid time off to ensure that Graves collected her regular salary during those three weeks.

“It was great,” Graves said, explaining that she was able to make arrangements for her father, Robert, to have long-term medical care. “It was really something after going through such a trauma.”

More than 30 of KPMG’s 16,000 employees nationwide got the same sort of assistance last year, said Joe Maiorano, the firm’s executive director of human resources. He explained that the managing partner of the worker’s office usually will send out a note giving the person’s name and a description of why the days are needed — keeping it vague out of respect for privacy — then people donate the time anonymously.

In order to be eligible for the program, workers have to meet the basic guidelines of the U.S. Family and Medical Leave Act. That means, for example, that they must have been working for KPMG for at least 12 months and that they can take up to 12 weeks off over the course of a year, Maiorano said.

They also must have used all their paid time off already. Most workers get five weeks off each year, which they use for vacation, sick days, errands, bereavement leave or whatever else they choose.

The essential difference, of course, is that people who use the federal leave do not get paid, while those KPMG workers do — assuming they have helpful colleagues.

California began a program last month that reimburses many workers if they have to take a similar leave, but the state’s maximum is only six weeks, and they receive only up to 55 percent of their lost pay.

Maiorano also said that his company’s program is not intended for employees who are sick; KPMG provides disability insurance to protect against that potential hardship.

I’ve always thought that paid time off is a smarter concept than establishing separate allowances for sick days and vacation days because when you separate out sick days, it punishes those workers who are your most dedicated.

They won’t call in sick when they really aren’t, so they end up working more days a year than those with different standards. And when one of their colleagues does call in “sick,” the dedicated ones often get stuck with a heavier workload on short notice.

In other words, companies reward dedication and professionalism by giving you more stress.

KPMG’s plan overcomes many of the common pitfalls of having the more generic paid time off. Most employees are allowed to carry over only one week to the next year, so the company will never be faced with a bill from someone who might have squirreled away 50 or 60 weeks of paid time off over the years. And the disability insurance makes sure that people can get help if a crisis strikes.

When companies provide separate sick days, it just begs for employees to abuse the system. If someone with an intolerant boss has to sign real estate documents or go to a child’s field trip, the worker might feel cheated using a full vacation day for those couple of hours. So he ends up calling in sick, and co-workers have to scramble with last-minute stress.

But if the company has paid time off (or at least a smarter boss), co-workers could know about the missing colleague in advance. They might still have to do extra work, but at least they could prepare for the absence.

Dave Murphy is the San Francisco Chronicle's workplace columnist. His Web site is at www.couchpotatoguide.com.