Looks like Amazon.com's (Nasdaq: AMZN) pugnacious bet on national sales tax reform is paying off.

The Seattle company says it is strongly supporting a proposed national law that would force online retailers to collect local taxes on more of their sales, ending a longtime loophole originally meant to help catalog businesses. The National Retail Federation, which has battled with Amazon on the sales tax issue, also is on board with the bipartisan Senate proposal announced today (the federation represents lots of brick-and-mortar retailers).

So how's that a win? Amazon has gone to some pretty extreme lengths to avoid being deputized as a tax collector for state and local governments, insisting that its shipping centers are different companies and even shutting down entire networks of third-party sellers when state lawmakers pass "Amazon tax" bills.

That behavior has caused a lot of turmoil for the ecosystem of smaller businesses that rely on Amazon. One example is the story of Shopobot, a comparison-shopping start-up that relocated from the San Francisco Bay Area to Seattle earlier this year specifically because Amazon axed its affiliate program in California.

But Amazon has said for a long time that it favors a national solution, rather than a hodgepodge of different state rules. Specifically, the company has supported something called the Streamlined Sales Tax project, in which states agree to a common set of sales tax definition and practices.

The common standards are important because each state taxes things differently -- sometimes wildly so.

Cue up today's bipartisan Senate bill, which uses the Streamlined Sales Tax program as a centerpiece of any national tax system for online sales.

So, while any retailer would certainly enjoy the fact that it didn't have to act as a big tax collector, and could price its products a little better to boot, Amazon clearly knew the days of tax-free Internet sales weren't going to last forever. It placed its bet on a national system, and made some pretty belligerent moves to reinforce that preference.

And it looks like that strategy is paying off.

There's no guarantee that this bill will actually become law, of course -- the federal lawmaking process is both arcane and volatile, and any tax vote will be a tough one in this economic climate. But it's got a lot of the hallmarks of something that could pass.

An interesting side note: Shoppers in Washington state already pay sales taxes on Amazon purchases, because the company's headquarters are here. But the state also says it's only collecting taxes on about half of the online and mail-order purchases by people living here, and that adds up to some big numbers.

If the new Senate proposal becomes law, Washington officials estimate that state and local government treasuries could raise about $242 million annually. That comes at a time when the state has been cutting billions from spending on education, health care, and other expensive government programs.

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Curt Woodward is senior editor at Xconomy Seattle. Reach me at [email protected]. Get story feeds and more on Twitter @curtwoodward and Facebook on.fb.me/curtwoodward.