What does a financial reform bill that was passed by Congress a few years ago have to do with what you pay for on-street parking in D.C.? More than you’d think, apparently.

In an email sent today, pay-by-phone parking app Parkmobile informed its local subscribers that it was increasing transaction fees—what each subscriber pays above and beyond the cost of parking every time they use the app—from 32 to 45 cents. The reason? The Dodd-Frank Wall Street Reform and Consumer Protection Act’s Durbin Amendment:

Beginning October 29th, transaction fees in DC will increase from $0.32 to $0.45 due to increased costs triggered by recent federal legislative reform enacted by the Dodd-Frank Wall Street Reform and Consumer Protection Act’s Durbin Amendment.

Needless to say, the email, which didn’t include much more of an explanation than that, provoked some local head-scratching.

Well, it’s not spam and it’s not a joke. According to the city officials who were briefed on the change, across-the-board increases in transaction costs imposed by credit card companies in the wake of the legislation would make Parkmobile’s business unsustainable in D.C. While Parkmobile used to pay around six cents from every 32-cent transaction cost to credit card companies, the increases pushed fees to the credit card companies up to about 30 cents a transaction.

According to Laurens K. Eckelboom, Parkmobile’s executive vice-president for sales, the company had been absorbing the costs of the new fees since March, and only opted to announce the increase now. “That was pretty ugly,” he said of the hit the company took when fees were increased.

Ironically, the Durbin Amendment was supposed to lower the amount that banks could charge businesses to process debit card transactions. But in response, MasterCard and Visa did away with discounts they offered merchants for small transactions. Still, as Greater Greater Washington notes, it’s a little odd that Parkmobile opted to blame the financial reform bill instead of the credit card companies.

Parkmobile is unveiling an alternative to the 45-cent transaction fee, though: Parkmobile Wallet. Like a SmarTrip card, the Parkmobile Wallet allows users to charge up their accounts with as much money as they want. In so doing, Parkmobile only has to pay one credit card transaction fee, and users’ fees go down to 30 cents for every time they use the app.

The company launched in D.C. in July 2011, and says that it has 400,000 local subscribers that have used the app some 4.5 million times.