After six months of meetings and analysis, we and the other members of the Mayor's Task Force on Tax Policy and Economic Competitiveness came to a simple conclusion: To turn around decades of decline and create opportunity for residents, Philadelphia must fundamentally change the way it finances city services. Right now, we are struggling to impose a 1950s tax system on a 21st-century economy.

When Philadelphia was a heavy-manufacturing town, firms were large and slow-moving. Suburbs were bedroom communities. We could tax wages and profits without worrying that workers and jobs would leave.

But in today's global economy, firms can simply pack up their computers and go. The task force found that nearly half of the city's 300,000 job losses since 1970 could be blamed on an excessive, outmoded tax structure.

Philadelphians are the most heavily taxed large-city residents in the United States. The city's small businesses are the most heavily taxed in the metropolitan area. As The Inquirer has documented, city tax administration is often inefficient, unfair, and impenetrable. No wonder businesses and jobs have fled.

When jobs leave, people follow. Our suburbs have added 1.4 million residents since 1970, but the city has lost 363,000. Those who remain are poorer and older. Philadelphia has the fifth-highest rate of poverty among large U.S. cities, behind only Detroit, St. Louis, Buffalo, and Milwaukee. If we do nothing, an additional 47,000 jobs and 100,000 residents can be expected to leave over the next 15 years.

In the task force's public meetings, many reminded us that good public schools and safety are essential if Philadelphia is to thrive. We agree. But no matter how educated and safe we are, we won't have opportunities for high school and college graduates if we keep taxing jobs and people out of the city.

We made four major recommendations for reversing the downward spiral:

Eliminate the gross-receipts tax, which stifles start-ups, and restart reductions of the wage and net-profits taxes in 2012. Wage-tax rates for residents should drop from 3.7 percent to 2.7 percent by 2025; for non-residents, from 3.4 to 2.4 percent. The net-profits tax should drop from 6.45 to 6 percent, and the city should immediately change the way net-income taxes are administered to attract new businesses and encourage growth when the economy rebounds. That would create at least 70,000 new jobs by 2025.

To protect funding for education and essential services, the city should rely more on taxing what doesn't move: land and buildings. The property tax need only rise by a modest one-half of a percent. To protect residents and shift the burden to commercial property - which would become more attractive with business- and wage-tax cuts - the task force proposes a $5,000 homestead exemption for homeowners. Most Philadelphians who see a property-tax increase would also see a wage-tax cut, meaning they would at least break even under this plan.

The city should take control of thousands of vacant and abandoned lots, holding some for future development and transferring others to community groups and developers who can return them to the tax rolls.

Finally, the city should keep cutting costs, returning savings to residents in the form of lower property taxes. With a 5 percent reduction in city spending, we could save $200 million a year by 2025 through better tax administration, more efficient use of city facilities, and gradual changes to city employee benefits.

During the economic crisis, we all reevaluated our family spending. City government must do the same. Just because we've put a budget crisis behind us doesn't mean we can lapse back into bad habits. Either we continue to lose jobs, opportunity, and residents, or we adopt a modern fiscal strategy, make the city competitive, and begin to grow again.

The authors are, respectively, the chairman, vice chairman, and members of the Mayor's Task Force on Tax Policy and Economic Competitiveness.