It’s always polite to leave a tip after enjoying a nice meal. And it would seem many D.C. government contractors adhere to the same principle when an election year rolls around.

It’s a tale as old as time in District politics: Any time a company wins business with the city, particularly in the construction industry, their executives tend to show up among the incumbent mayor’s campaign contributors.

It’s not corruption, per se—these firms normally aren’t trading campaign cash for contracts, but rather trying to keep things stable after they’ve found partners in government willing to work with them. Even still, it’s normally worth checking to see just how thoroughly a campaign finance report is populated with these contractors before declaring a big fundraising haul a show of grassroots support.

Thumb through Mayor Muriel Bowser’s latest filings to see some of this pattern in action. Between Feb. 1 and March 10, Bowser raised at least $13,100 from D.C. contributors who said they worked for a total of 42 companies that either currently do business with the city or have won contracts previously. Those dollars will be matched five times over via the city’s public financing system. Bowser raised another $5,700 in donations from people at those companies who live outside the city, which won’t be matched.

That amounts to about a tenth of Bowser’s entire haul from D.C. residents for the fundraising period (about $121,000 in all), and makes up a similar share of her cash from non-District contributors (a total of $61,200). And that could still leave plenty of firms unaccounted for—Loose Lips checked D.C.’s procurement database, D.C. Council records, and company websites to find evidence of any government work, but some could still fall through the cracks.

The new public financing system has certainly limited the influence of D.C. contractors willing to open their wallets. The maximum contribution is $200 for individuals, compared to $2,000 under traditional campaign finance rules, so politicians are more incentivized to pursue true, small-dollar donations.

But Bowser’s report also helps demonstrate how companies can work their way around these limits. Take Freestate Electrical, for instance.

The company, which lists work on the University of D.C.’s student center among projects on its website, is based in Laurel. But many of its electricians live in the District, and seven chose to give the maximum $200 to Bowser, contributions that will be worth $7,000 to her campaign once she receives matching funds. Another nine employees who live outside D.C. added their own $200 checks.

The Citadel Firm, which has contracted with the Department of General Services to maintain D.C. buildings, managed something similar, with four D.C. employees handing over checks. J.L. Terrell Construction, which has done work on both DGS- and D.C. Housing Authority-owned properties, matched it with four contributions. Two direct employees of the company were listed as donating money, while two others share an address with founding partner Keith McDuffie, cousin of outgoing Ward 5 Councilmember Kenyan McDuffie and a listed subcontractor on the controversial Intralot sports betting contract. Nine other companies saw multiple employees make contributions.

Developers are traditionally hefty campaign contributors, and while they may not win contracts from the city in the same sense as other companies, they certainly have a lot to gain from maintaining good relationships with the administration, particularly should they hope to win projects on public land. Bowser raked in cash from 14 of the region’s largest builders, earning a total of $2,800 from D.C. residents and $1,800 from executives outside the city, certainly large sums but nothing compared to the industry’s influence on campaigns of years gone by.

As is tradition, Bowser also scored cash from some of her own employees: D.C. Public Schools Chancellor Lewis Ferebee and Department of Small and Local Business Development Director Kristi Whitfield each gave her $200. Sheila Miller, who oversees the New Communities Initiative, added $50.

Bowser’s totals (and her $2.7 million in the bank) put her firmly ahead of At-Large Councilmember Robert White, who managed to raise about $56,000 over the same time period. He finished with $816,000 in cash on hand. No word yet from Ward 8 Councilmember Trayon White, who received an extension until March 25 to file his report.

Without the benefit of incumbency, Robert White’s report doesn’t have quite the same roster of contractors stocking it. Instead, some of his notable names include some staples of District politics (there’s Holland and Knight lobbyist Janene Jackson and Venable partner Claude Bailey), One Fair Wage organizer Ryan O’Leary, and former D.C. planning director Harriet Tregoning. There’s even frequent development disrupter Chris Otten, who pitched in $27.