Municipalities are increasingly levying taxes on home-based businesses. Zoning laws originally drafted to prohibit people from working out of their homes are being revised to encourage home businesses, and then cities begin to tap into this small, but growing, source of revenue.

• Tampa, Fla., for example, realizes $8 million annually from home-based businesses and professionals -- 2 percent of the city's general operating budget.

• Nationwide, about 20.7 million households -- one in five -- engage in some form of home business -- up from just 14.2 million in 1990.

• Municipal tax officials report that 20 percent to 50 percent of new business licenses they now issue are for home businesses.

• About 13 million households rely on home businesses as their primary source of income -- averaging $80,000 in gross receipts annually.

There are also about 9 million households with a part-time home business -- with average receipts of $10,000.

Tax officials say the most difficult part of raising revenue from a home business is simply finding it. Authorities say owners of home-based businesses often resist submitting to regulation, licensing and taxing.

In Los Angeles, a group of screenwriters has brought suit against the city, charging that the city is trying to license writers -- in violation of the First Amendment. The city wants to impose a tax of $5,900 on a $1 million payment for a screenplay.