On line 19 of the state income tax form is a space for the "Utah use tax." Residents are supposed to figure and report the Utah sales tax due on any out-of-state mail order or phone purchases. While many Utahns buy items this way, most leave line 19 blank.

As a result of their failure to report this use tax, Utah government is losing an estimated $10 million a year in revenue. So widespread is the practice of ignoring the law that only $33,000 in use taxes has been reported so far this year, despite the fact that more than 40 percent of state income tax returns have been filed.If the collection of in-state sales taxes were handled the same way, Utah would quickly go broke.

Utah is not the only state with this problem. Most of those that have sales taxes report the same difficulty.

Many are trying a different approach to getting their money. Eighteen states have passed laws that make the seller responsible for the sales tax instead of the buyer. Under those laws, the seller must collect the sales tax due in the state where the buyer lives and remit it to that state.

Idaho is the latest to take this step. The Idaho Legislature, saying that the state is losing $5 million to $7 million in uncollected sales taxes, passed a so-called "catalog law" this week. It requires out-of-state phone and mail order businesses to assess the Idaho sales tax on purchases by Idaho residents and forward it to the state.

Clearly, this creates a bookkeeping expense for mail order firms. But in-state companies also are burdened by collecting sales taxes, yet they also reap an advantage. In Utah, for example, businesses pay the sales tax money they collect to the state each quarter. In between payments, they use this "float" to earn interest that may offset some of the collection cost. Mail order firms could do the same thing.

Requiring the out-of-state seller to collect sales taxes has been challenged in several unresolved federal court cases. But Idaho chose to leap into the fray without waiting for a possible U.S. Supreme Court decision that could be years down the road.

Utah officials - chiefly, the governor's office and the Tax Commission - also would like to have the out-of-state seller responsible for sales taxes, but they prefer to support a national approach to the problem. Bills have been introduced in Congress the past two or three years to require mail order firms to collect local sales taxes. None have passed yet.

Given the fact that state and local governments depend heavily on the sales tax, the failure of people to make such payments - whether willfully or out of ignorance - hurts. It is a problem that needs to be corrected and zeroing in on the seller instead of the buyer makes sense.