THE GOOD NEWS on the San Francisco budget front is that the supervisors are taking the initiative and helping set the agenda for budget talks – long before Mayor Gavin Newsom actually releases his fiscal plan for next year. Several groups are actively talking about ways of raising new money: There's discussion of a sales tax for public health, a parcel tax for the schools, and a tax on employers who don't provide health care. The real estate transfer tax pops up in conversations. So does closing the loophole that lets law firms avoid paying business taxes. It's understandable: city services are starved for money, and the city desperately needs to find more ways to bring in cash.

But there's a big picture that's badly missing here: the city's tax structure is a mess, a hodgepodge of antiquated taxes and special revenue programs stitched together with duct tape and baling wire – and in the end, it's a pretty regressive system. There are all sorts of quick, short-term fixes, but the supervisors ought to be going beyond them and talking about a complete overhaul of the ways San Francisco brings in money.

Just about everyone who lives or works in San Francisco pays some form of tax. Muni fares are, in effect, a tax on getting to work. Fees for public recreation facilities are a tax. City license and permit fees are taxes. There's nothing wrong with that – but it all needs to be part of the discussion.

Right now big businesses and wealthy individuals pay way, way less than their share of the cost of running the city. The local business tax hits small companies harder than big ones (and taxes payroll, not the best measure of a company's income, profit, or wealth). The user fees are paid overwhelmingly by the lower end of the socioeconomic spectrum. And it's hard, sometimes almost impossible, to adjust fees and taxes in a fair way when the city needs more money.

It's more and more important for the city to be able to properly raise its own money. Washington, D.C., and Sacramento are cutting aid to cities, leaving places like San Francisco increasingly on their own.

So instead of continuing to tinker with a messy, creaking old financial machine that's about to collapse, it's time to talk about scrapping the whole thing and starting fresh.

There's no shortage of ideas about local taxes and revenue sources. A progressive system might shift from a payroll tax to a gross-receipts tax (or keep some version of the payroll and add a gross-receipts tax on top of it, and skew both levies so that bigger companies pay a higher percentage). Taxing commercial and possibly residential rents ought to be on the table. So should some version of a city income tax. The real estate transfer tax could be altered to hit hardest on speculators who buy property and flip it quickly for profits. The list goes on and on.

But none of these things should happen alone. It's hard to get any tax passed these days, even in San Francisco – and the progressives on the board need to take the lead in changing the entire discussion. A comprehensive revenue overhaul wouldn't just be a set of tax hikes – for most people in the city, it would probably amount to tax cuts. A vehicle license tax, for example, could be paired with a cut in Muni fares. Charging the biggest and wealthiest employers more could mean charging small businesses less.

Nobody else in the country is looking for ways to shift the tax burden off the poor and onto the rich; San Francisco ought to be leading the way.

Sup. Aaron Peskin, as board president, ought to take the lead on this and appoint a blue-ribbon panel of tax experts – including everyone from San Franciscans for Tax Justice to the city employee unions to small-business groups (he could even invite a downtown representative or two to participate) – and give that group a mandate to meet publicly, hold hearings, and come back in six months with a proposed charter amendment that would completely change the way the city collects money. The goal: shift the burden off the poor, make the rich pay their fair share, discourage bad economic behavior, encourage job creation, allow for flexibility in hard times – and bring in another $200 million a year.

It could be one of the most important political causes and significant economic advances in many, many years. We're waiting.