Microbiology junior Jonathan Lenz knows the taxes he owes Michigan from Web purchases could start piling up.

Six percent sales and use taxes are levied on Internet and mail-order purchases made in Michigan, but little of it is collected, according to the nonpartisan Senate Fiscal Agency. In October 2001, the agency estimated Michigan was losing $100 million to $300 million in uncollected sales and use taxes, an amount that has undoubtedly grown since.

That's because taxes on Internet and mail-order purchases are paid on a voluntary basis, Senate Fiscal Agency economist David Zin said.

"Not surprisingly, a lot of people don't do this," he said. "The only way the Treasury can get the money is to do extensive audits and go through (receipts)."

In an attempt to help solve the state budget crisis, Gov. Jennifer Granholm said she supports efforts to begin enforcing collection of the sales and use taxes.

"The problem is we don't have a mechanism for collecting the tax," said state Rep. Gretchen Whitmer, D-East Lansing. "We're cutting health care, education, higher education. If we can collect taxes like these, we might not have to make cuts or the cuts can be smaller."

Michigan is a part of a multistate coalition that agreed in November to make revisions to tax laws that would allow states to collect, but because of the changeover in many legislatures, the process has been slowed.

The coalition is working to create common definitions for states on taxable goods and services. The group meets today and Friday in Tampa, Fla. Dale Vettel, administrator of the Treasury Department's technical services division is representing Michigan at the meeting.

Orange juice provides an example of a product with differing definitions, state economist Zin said.

"In one state it could be defined as a beverage and be taxed," he said. "But in another state it could be defined as a fruit and taxed at a different rate - or not taxed at all."

The endeavor stems from a 1992 U.S. Supreme Court decision that left the door open for states to simplify their tax definitions and then collect on all interstate purchases.

Like Michigan, many states involved are hoping their work will help solve budget issues.

And the sooner, the better. Online spending during the 2002 holiday shopping season was up 24 percent from 2001, according to a report from Nielsen NetRatings, Goldman Sachs and Harris Interactive.

Some might argue collecting taxes from online consumers will hurt the growth of e-commerce, but not all students agree.

Lenz, who spent just under $100 on Web purchases last year, said sales taxes usually don't amount to much.

"The shipping charges are more of a deterrent than taxes are," he said.

Staff writer Joey Guillen contributed to this report.