SmugMug has called Mountain View home for more than a decade, since it moved out of the founders’ family home. But as the city considers a tax that would charge all but the smallest businesses an annual per-employee fee, that could change where the photo-sharing service plots its growth.

Last week, SmugMug opened its first office outside of Mountain View in San Francisco. The 8,250-square-foot office at 390 Fremont St. is a home for its recent acquisition, rival photo app Flickr. The San Francisco outpost will have 25 to 30 employees, including some moving north.

“We thought it was important to keep the team close to their homes and the city that they love and still have it be a part of the identity of Flickr,” said Ben MacAskill, SmugMug’s chief operating officer.

The reconfiguration would leave SmugMug with 40 staffers in Mountain View. Under a new business-license fee the City Council is considering, SmugMug would pay a flat fee of $400, since it has fewer than 50 employees. Once companies grow past that, they pay an additional fee per employee, starting at $75 and rising with the total number. The council will vote this month on whether to place the tax on the November ballot.

Critics say the move could spur businesses to move jobs elsewhere. SmugMug could be a case in point: MacAskill notes that its S.F. office has room for the company to grow there.

“We would definitely re-evaluate if it became too costly or too painful,” Ben MacAskill said. “We love Mountain View — it’s part of our identity. It is not so important to our identity that we could not move.”

There’s no immediate cost savings for SmugMug to employ people in San Francisco. In 2012, San Francisco began to phase out a payroll expense tax that charged businesses a percentage of what workers were paid. The tax, once as high as 1.5 percent, was originally set to expire this year. Because revenue from a replacement gross receipts tax was lower than expected, the city expects to charge businesses a payroll tax rate of about 0.5 percent starting in July. That makes San Francisco, at least in the short term, a more expensive place to employ people.

Mountain View hasn’t changed its $30-a-year business license fee since 1985. Google and the Bay Wash coin-operated laundry pay the same. Council members have said raising the fee could generate $6.1 million a year, which would go toward fixing traffic problems and the regional housing crunch.

Mayor Lenny Siegel said he thinks a higher fee would be low on the list for reasons why a company would leave his city.

“The biggest disincentive to locating in Mountain View right now is the difficulty recruiting and retaining workers because housing is so expensive and we have a very poor public transportation system,” said Siegel, adding that money raised through the tax will help the city address those issues.

“If we’re lucky, some of the companies won’t expand here and they will expand elsewhere, where the workers live,” said Siegel, later adding, “I’m not saying, ‘no growth.’ At a certain point, growth becomes too fast.”

Down the road, Cupertino, Apple’s hometown, is also considering a similar employment tax, as cities grapple with the surge in jobs and not enough regional housing built over the years. But such taxes can face a backlash from the business community.

Local business organizations have already expressed concerns about Mountain View’s tax. In Seattle, Amazon opposed a tax that would charge certain businesses $275 per employee, raising money for homeless programs and affordable housing. This week, just a month after they passed the tax, Seattle council members repealed it.

Amazon Vice President Drew Herdener said in a statement that the council’s vote was “the right decision for the region’s economic prosperity,” and said the company would continue to invest in nonprofits that address homelessness.

Meanwhile, SmugMug is working on welcoming Flickr employees to their new home. Almost the entire Flickr team joined SmugMug after it acquired the business from Verizon’s Oath division, MacAskill said. The office is steeped in history: Submarine engines were manufactured there during World War II. Soon, its walls will feature a new chapter for the city, with photos from Flickr users a testament to how mobile apps have changed the landscape.

“We think it’s an exciting platform and exciting community and we want to invest in it properly,” MacAskill said.

Wendy Lee is a San Francisco Chronicle staff writer. Email: wlee@sfchronicle.com Twitter: @thewendylee