The state plans to expand its online listing of tax scofflaws later this month.

On Tuesday, the Department of Taxation sent out letters to 18 tax offenders who owe at least $100,000 in back taxes, penalties and interest, informing them they will be listed on a Web site unless they made arrangements to pay up.

The initial results of the online program started in April have been meager compared to the millions that are owed. But state officials say that was expected.

"We expect to have more success," said Sandy Yahiro, Tax Department deputy director. "I believe that as we send these new letters out, each time it will only get better for us."

Hawai'i went online on April 24 with its Web listing of tax offenders, following other states that have taken to identifying online people and businesses with big unpaid tax bills. The initial posting, a Web page linked to the department's site, included names of 39 people and five companies who owed the state a total of more than $17.4 million.

Yahiro said the state has decided to expand the program by adding more names every two months even though initial results have been somewhat disappointing, with only a few thousand dollars being collected.

Letters sent before the list's April debut only yielded a few responses from people agreeing to settle up before their names were made public.

The state said one taxpayer on the list owed the state $3.2 million. Yahiro said the person has agreed to start making payments, but is disputing the amount.

Another person who owed about $500,000 also has started making payments, she said.

But overall, the results from posting the names online has been underwhelming. Yahiro said that was to be expected since some of the tax bills were from a decade ago, while others were for taxpayers who now live on the Mainland.

For example, among those listed on the Web site is Waiakea Villas LLC, a company owing $636,148 in general excise and transient accommodations tax. Waiakea Villas' Hilo property went into foreclosure about two years ago and its developer, Simon Bebb, recently filed for bankruptcy.

"We felt the first round might not yield us much," Yahiro said, adding that some of the $4.6 million in back taxes owed by the 18 taxpayers now receiving letters is more current.

"I'm cautiously optimistic that as we produce new lists they'll be more fruitful."

The Tax Department has been creating more programs to collect delinquent taxes and rake in taxes it might not have received because of underreporting of income or failure to file returns. In addition to trying to get more tax auditors, the department has started a one-month amnesty for people to pay back taxes without penalties.

Yahiro said state officials hope that posting the names of tax scofflaws online will boost collections. The Tax Department wants to gain $5 million from the program in the year starting July 1.

"There was quite a bit of work that went into setting this up," she said. "I believe as we move down the list we'll get more money."