JOHNSTON — The local tax bill for a single-family home of average value has risen 11.9 percent since early 2007, according to information compiled by the Rhode Island Department of Revenue.

The average value for a single-family home was $209,957, and the total annual taxes owed were $3,745 in early 2007 — before town officials levied extra taxes that year to cover deficits. In the budget year that ended June 30, 2008, the tax bill for a single-family home of average value was $4,191.

The steeply increasing tax load has been a hot subject in this season’s political contests.

In their efforts to cast town officials as tax hikers, several opposition candidates — including Mayor Joseph M. Polisena’s opponent, Raymond F. Acciardo Jr. — have cited percentage increases in the teens.

Tracing the changing tax burden in recent years has been complicated, thanks to soaring real estate values and the establishment of a new homestead exemption, which gives taxpayers a 20-percent break on owner-occupied home real estate assessments.

For those reasons, the increase in the tax rate alone, from $17.84 per $1,000 of assessed value to $18.91 per $1,000, did not convey the full extent of the taxes levied on many homeowners last year.

For the budget year that started July 1, real estate values are stable and officials have left the tax rate alone at $18.91 per $1,000 of assessed value, loudly declaring their success at sidestepping any tax increase this year and challenging critics who have tried to quantify the previous hikes.

At the request of The Journal, Peder Schaefer, chief of the DOR’s Division of Municipal Finance, calculated the average value for a single-family home taxed in the fiscal year that ended June 30, 2007.

He said the initial tax obligation for such a home, valued at $209,957, was $3,745, not including a special tax that was levied late that year as part of the town’s fiscal recovery plan.

In the next budget year — from July 1, 2007 to June 30, 2008 — tax bills were affected by updated real estate values, a higher tax rate and the town’s offering of a homestead exemption.

The average value for a single-family home to be taxed in that year rose to $277,078, Schaefer said.

If the same home qualified for the 20 percent homestead exemption, its taxes would have been billed at a value of $221,662, he said.

The total tax bill, after the exemption, amounted to $4,191, he said. This is an 11.9 percent increase, he said.

The scenario does not reflect the experience of every taxpayer whose home was close to the starting value — the average — calculated by Schaefer.

For instance, the tax bills for one Truman Street home in the fiscal year that ended June 30, 2007, were based on an assessment of $209,200. The home’s value was just below the average for single-family houses.

But for whatever reason, the assessment that affected the next fiscal year’s taxes, $265,500, fell below the average of $277,078.

After applying the homestead exemption, the total tax bill came to $4,016, reflecting an increase of 8 percent.

Also, during the same period, elderly taxpayers and veterans were eligible for exemptions that might have given them tax cuts.

Robert Parker, the mayor’s chief of staff, put a heavy focus on that scenario when he presented Polisena’s tax policy to the council in late June 2007.

He randomly picked 25 houses and analyzed the tax impact on those houses.

Polisena could not be reached for comment on the new tax information yesterday.

Town Hall still hasn’t provided assessment information that The Journal requested in advance of September’s Democratic primary.

At the time, Democrat Councilwoman Stephanie P. Manzi faced a challenger, Lorraine M. Natale, who said taxes had increased 13 percent.

Natale was unable to explain her calculations in detail.

Yesterday, Manzi said she would like the town’s finance director to confirm Schaefer’s numbers if possible.

She acknowledged that many homeowners saw increased taxes last year due to higher assessments and the need to cover deficits.

“We had to raise a certain amount of funds,” she said. “Unfortunately, we didn’t have a bigger tax base to spread that out and the homeowners got hit the hardest. Now, we’re working together to expand the tax base so everything is minimized across the board.”

mreynold@projo.com