When we use computer-assisted reporting for our government coverage, salary data is often at the top of our list.

We obtain government payrolls and rank them. We compare median salaries of teachers among our school districts. When a government worker gets suspended for official misconduct, we don't report just that. We write that the worker was suspended from a $90,000-a-year job.

But salary data is just the tip of the iceberg in reporting on government workers and their benefits. There's police overtime, government-issue cell phones and credit cards.

And in New Jersey there's the matter of sick and vacation time. Seemingly innocuous, except, as we found, that local government agencies are now on the hook for nearly $1.5 billion to reimburse employees who fail to use their allotted time.

Ever since the Great Depression, civil servants in New Jersey have essentially been guaranteed 15 paid sick days a year. Over time, government agencies began allowing workers to carry unused days over into sick day banks, a practice later codified in union contracts.

It's a progressive benefit intended to protect workers who suffer prolonged illness. But in the modern era, it has become a bonanza for retirees. As public employee unions gained strength in the 1970s, they managed to negotiate mandatory payouts for unused sick and vacation time.

In almost all cases the payouts are made to retirees at their final pay rate, not the salary at the time the days were banked.

The Star-Ledger was certainly not the first paper to notice how common it had become for a police chief or schools superintendent to collect a six-figure payout - on top of a generous pension - just for retiring.

In fact, when I was with a regional paper in New Jersey a few years ago, we did a pretty good CAR story that looked at the potential cost of this system.

But nobody had ever been able to report precisely what the statewide impact was, and thus we had a mission.

When it came to gathering data, we had one thing going for us. The state had recently enacted new regulations that required municipalities to annually calculate the value of "compensated absences."

We found that school districts had been making the calculations for years and listed the amount as a long-term liability on their annual audits.

That was the good news. The bad news was that none of this information was available electronically. We wanted a number for 1,177 different agencies throughout the state and it was all on paper. We discovered that all of the paper ends up in one place: Trenton.

So with a research assistant and laptop in tow, I made a series of visits to the state capital. It took us about six days to pull the 1,177 documents out of filing cabinets one by one, find the sick time number on each and enter them into a spreadsheet.

Once we had the numbers it was easy to add it all up and come up with the $1.5 billion total.

More challenging was coming up with a method for compiling town-by-town statistics. In addition to the state's 566 municipalities, we had to account for school districts and county agencies that collected taxes across town borders.

Since we wanted to measure the impact on the basis of property taxes, we used property tax data to help us divvy up the burden.

For example, employees of the West Essex Regional district had $400,000 in the sick-time bank. Roseland is a town served by the district, and about one quarter of the district's tax base is located in Roseland. Therefore, we assigned one quarter of the obligation to pay West Essex retirees to Roseland residents.

We did the same with the obligation to county employees so at the end of the process, we had one figure for each town that incorporated what was owed to municipal workers, school employees and county employees.

After we had a single number for each town, we wanted to add context.

Obviously, the biggest cities would have the most employees - and likely the highest total obligation.

Yet these towns would also be able to spread their obligation among a larger base of taxpayers. So we needed to come up with a way of quantifying the number. We came up with two.

First, we did a simple per-capita calculation. Then we plugged the number into the town's property tax formula and expressed it in terms of the average homeowner.

We used both in the story. Per capita, we decided, was an easy-to-understand ratio that generally put the total obligation into context. The average homeowner cost, meanwhile, was a more precise measure that told readers "This is exactly what it's going to cost you in coming years."

We found that in a tiny urban enclave called Harrison, the average homeowner was on the hook for nearly $3,100. Overall, the debt was $251 per person in the state's 30 cities, but only $152 per person in the suburbs.

We also found that individual golden parachutes were being proffered all over the state. In one of the audits we pulled, for a tiny rural community called Stillwater, there was a footnote from the auditor explaining that the town's obligation was unclear, pending resolution of a conflict with a soon-to-retire police chief.

Upon closer examination, we found a community where the police force could be counted on one hand, the number of annual crimes on two, and the police chief was walking away with a severance package of $117,587 for sick and vacation time he didn't use.

After the story ran, a reader tipped us off to another case that lead to a follow-up: The police chief in Jersey City had recently been granted a compensation package that provided him with an instant bank of 150 sick days-days he could cash in upon retirement.

That wasn't necessarily unusual, except that the chief had already retired once from the force, as a lieutenant, and cashed in a six-figure payout. Now he was in line to get a second helping of taxpayer generosity.

There were, of course, arguments included in these stories for why such payouts are justified. Unions told us that because these benefits are often negotiated for their rank and file, it means the unions had to give up something else to get such a deal.

Still, the point of our stories was not to pass judgment on the system. Rather, our goal was to tell readers the real cost of such a system - a figure that had been unknown until we completed our project.

Read the story, "Cashing Out," online at www.nj.com/specialprojects.