Arguments over the past few months from various government leaders on behalf of rolling forward property tax millages have left out a major element of the process.

The state constitution requires rates to be adjusted down with rising property values after the quadrennial reassessment so taxing jurisdictions receive the same revenue that they would have received prior to reassessment.

The constitution, however, also allows taxing jurisdictions to roll forward and raise that millage rate to its old level, capturing additional revenue.

A consistent theme among Ascension Parish officials on rolling forward is that their respective jurisdictions need that revenue to keep up with growth. No doubt, even in a slower economic period, the parish is still grappling with the added costs of growth.

The once-every-four-years reassessment is for real property only, basically land and buildings. Rolling back and rolling forward is a function that applies to that reassessment only.

Residents and the media naturally focus on this process because it can affect everyday people in their pocket books if, for example, home values rise and property tax liabilities increase.

What gets missed in this discussion, though, is that other property categories, such as those that apply to industry, a major category in Ascension, are reassessed every year. New development in all property categories also contribute to the tax rolls annually.

These annual additions to the rolls result in new revenue each year and do not have the required downward adjustment of property tax rates or any resulting roll forward process.

The fact is, in many cases, rolling forward brings added revenue on top of added revenue even with the downward adjustment in tax rates. That first batch of revenue is also normally much bigger than the smaller amount that results from rolling forward.

Estimates from outgoing Ascension Parish Assessor Renee Mire Michel bear this out.

These are early estimates, by the way, and are not based on what is expected to be the final taxable assessed valued by the time bills go out at the end of the year.

Last month, Ascension Parish Sheriff Jeff Wiley rolled forward the property tax for his office from 14.35 mills to 14.48 mills, netting an additional $119,819.84 this year.

Before rolling forward, other annual additions to the tax rolls had boosted estimated revenues from $12.67 million in 2011 to $13.23 million in 2012, an increase of $555,086.64.

The Ascension Parish School Board rolled forward several millage rates earlier this summer.

The largest of the property tax rates, 21 mills for school employee salaries, was rolled forward from 20.82 mills to 21 mills, netting $165,909.99 this year.

Before rolling forward that tax, other annual additions to the tax rolls had boosted estimated revenues for the employee salary tax from $18.38 million in 2011 to $19.19 million in 2012, an increase of $812,890.56.

The Parish Council rolled forward 17 of 21 millage rates for parish coffers and various dedicated taxing jurisdictions under council purview.

Before rolling forward, combined parish revenues would have risen from an estimated $21.89 million in 2011 to an estimated $22.77 million in 2012, an increase of $880,158.60. Rolling forward added an extra $196,883.

The issue, then, when it comes to rolling forward, is whether that extra revenue is necessary when local governments already are expecting revenue growth.

It’s not a question of “if,” but “how much.”

David J. Mitchell covers Ascension Parish government for The Advocate. He can be reached at dmitchell@theadvocate.com.