

Thousands of homeowners who challenged assessments on their own fared worse than those with similar appeals who were represented by two big tax firms.

The county miscalculated nearly a million exemptions, which were small but added up to hundreds of thousands of dollars over seven years.

A county program called Carry Forward virtually guaranteed some homeowners 5% to 9% decreases each year — but those who didn’t qualify paid a price.

Not filing an appeal for several years was one reason but another involved the varying criteria of the Carry Forward process, which the county barely publicized.

Business owners who have not filed a challenge — whether they thought they were already underassessed or were not fully informed of the advantages of appealing — have been hit even harder than homeowners who haven’t filed.

The halt means taxpayers who have not been awarded one of the overhaul’s substantial assessment reductions will continue to pay for the tax savings of those who have been.

You can file an appeal for free on the county’s Assessment Review Commission website.

Thousands of Nassau property owners who had not challenged their assessments since the process was overhauled in 2010 filed appeals this year.

Nassau extended the deadline for accepting property tax assessment appeals, a day after Newsday reported the system has created stark differences in tax bills.