A day before Uber’s massive initial public offering, San Francisco proposed a bill seeking to tax the riding-hailing giant and other tech companies on the funds raised in their IPOs.

The so-called IPO tax, introduced by San Francisco Supervisor Gordon Mar in April, would raise the employer payroll tax on stock-based compensation to 1.5% from the current rate of 0.38%, restoring it to the rate it was in 2011, just before the city cut the tax in a bid to attract more tech business.