A tax-reform group is considering a lawsuit against the city's Board of Revision of Taxes aimed at forcing it to establish a fair system of assessing property.

If the reform group, Philadelphia Forward, can find funding and a cross-section of property owners willing to challenge the system, it will have a two-pronged attack on a tax assessment system that is in the midst of a slow-motion overhaul, announced in early 2004 and still probably two years away.

For weeks now, the first prong has been clear.

Philadelphia Forward's Brett Mandel has been urging taxpayers to appeal the 413,000 reassessments sent out by the BRT in August.

Mandel calls the reassessments a "backdoor tax increase that is illegal, improper and unjust."

According to a BRT spokesman, about 5,000 appeals have been filed so far. The deadline for appeal is Monday.

At a private meeting this week, Philadelphia Forward convened a group of stakeholders to discuss the potential for a lawsuit to force the BRT to carry out a full-value assessment system.

"The lawsuit would be aimed at getting the BRT to follow the law, which says that all properties must be assessed uniformly," Mandel said. "The law says that market value should equal about what you paid for your house . . . If it were up to me and I had the resources, I'd sue yesterday. The system is clearly not going to change without an external push."

Jonathan Stein, general counsel of Community Legal Services and a former member of the city's Tax Reform Commission, said, "We're taking a hard look at this. It would be major litigation and you don't jump into it after one meeting."

Individual appeals of reassessments are valid, he said, but "they miss the forest for the trees. They miss the bigger inequities in the system . . . It's a very very unfair system. It's another case of the poor pay more."

In 2003, the city's Tax Reform Commission sharply criticized the current assessment system, noting that it hurts the city's working-class homeowners. Mandel, who also served on the commission, chaired the real estate tax working group.

"Lower-priced properties are typically assessed at higher fractions of their value than higher priced properties. Thus, the assessment system results in a higher tax burden [in percentage terms] upon poorer households than upon more affluent households," the study asserted.

The commission recommended a full-value system that would make the entire process more transparent.

By 2005, the BRT signed a $4.4 million contract with a Colorado firm to install a "state of the art, computer-assisted, mass appraisal system" that would enable the BRT to assess properties at full market value.

But by late 2006, the BRT decided to delay implementation of the system until after the 2007 election cycle.

Charlesretta Meade, BRT chairman who replaced David Glancey earlier this year, could not be reached for comment.

In her place, a media consultant speaking for the BRT said the new system would be ready by late 2008, which would mean new assessments could be sent out in the summer of 2009 for the 2010 tax year.

But the BRT's Web site says that the board will not implement the full-value system until tax relief protections such as homestead exemptions and property tax "phase-ins" are approved by the City Council and the state Legislature.

Democratic mayoral candidate Michael Nutter, who tried, unsuccessfully, to reform the assessment system while in Council, says the city "has had an inefficient and unjust property tax system. Because of years of an ad hoc and piecemeal system process, identical properties have widely different assessments."

While supporting a "fair and accurate citywide property reassessment," Nutter said he also wants a homestead exemption and a cap and deferral plan, limiting tax increases to no more than 10 percent per year. *