The tax rolls in Riverside have swelled through the city’s six-month amnesty program.

In figures as of Feb. 7 (a couple weeks short of the six-month deadline), the amnesty brought in 99 new businesses based in the city, and 33 from outside the limits.

This represents an increase of 0.6 percent from the 20,500 active accounts registered in the city. The city of Riverside has 304,051 residents in the state’s 2010 estimate.

“We started on the front end engaging the chamber of commerce to get them involved,” said Scott Catlett, Riverside’s assistant finance director. “We were making this not an adversarial action but a collaboration.”

Chamber officials were helpful in going over the words and tone of a letter sent to businesses offering the amnesty, said Catlett.

The city did “aggressive outreach” through the chamber, and notices in utility bills, a city magazine for residents and on the cable access channel’s “Riverside Today” show.

A city ordinance mandates businesses that generate income in the city to pay an annual city business tax. The minimum tax is between $108 and $130 for a typical small business, and increasing for larger businesses, according to a city news release.

The city feels it loses millions each year because of businesses that don’t pay the tax.

“It’s an unfair burden on those who follow the rules and pay the business tax,” said Nancy Hart, who chairs the city’s finance committee.

Penalties can be 100 percent of the tax unpaid. During the amnesty period, the city did not levy those penalties.

“We don’t want to unfairly penalize those businesses that may not have realized that they need to pay a Riverside business tax,” said Paul Sundeen, chief financial officer of the city.

In the next three or four weeks, staff will come to the finance committee and the City Council with a proposal to use a consultant to run a voluntary program for city businesses to share names and addresses of vendors they use, said Catlett. The firm would also analyze lists to find other outside companies that do business in Riverside.

If a vendor does not have a business tax certificate, they will be contacted by the city and given another 60 days to pay the tax and comply with the ordinance, according to the city’s news release.

The city has a field inspection program with three inspectors locating businesses. Catlett said staff believes they miss a number of home businesses, which are more prevalent lately with advances in telecommunications and desktop publishing.