A growing movement to collect taxes on Internet transactions could affect online retailers like Amazon.com Inc. (AMZN), but consumers have grown so comfortable with e-commerce that any impact on sales would likely be small.

Over the past few weeks, Seattle-based Amazon has protested legislation in North Carolina and California that would require e-commerce companies to collect sales taxes if they have marketing affiliates - people who get a sales commission from links on their own Web sites - in those states. Hawaii and Connecticut are also weighing similar laws.

Amazon says efforts to force it to collect taxes based on marketing affiliate relationships are "unconstitutional" and would backfire if Amazon were to sever ties with its advertising partners.

But analysts said taxing Internet transactions would likely have a minor impact on the business of retailers like Amazon. Bruce Cundiff, an analyst at Javelin Strategy & Research, said Amazon has firmly established its reputation and relationships with online shoppers, and estimated a sales tax might reduce the company's overall revenues by "low-single digit" percentages.

The growing movement to tax Internet transactions comes as critics of the status quo argue Amazon and other Internet retailers enjoy a significant advantage over brick-and-mortar competitors, which collect sales taxes.

It also comes as many states wrestle with large budget deficits amid the continuing recession and look for new sources of revenue.

With $19.2 billion in revenue last year, the world's largest Internet retailer has become a tantalizing target. A recent University of Tennessee study estimated that uncollected taxes could cost state and local governments more than $11.4 billion in lost annual revenue by 2012.

Consumers are supposed to pay tax for items they buy online, but state governments have no way of enforcing the law and cannot require out-of-state retailers to collect taxes if those companies have no "physical presence" in the state. North Carolina and California are trying to define marketing affiliates as commissioned sales representatives with physical presence in their states.

The retailer has called the initiatives "unconstitutional." Amazon said that cutting relationships with marketing affiliates in states imposing Internet taxes would deny companies the advertising fees they currently receive and generate no new tax revenues from sales on Amazon.

Bill Fox, co-author of the University of Tennessee study, said changes under consideration would merely bring Amazon and other Internet retailers in line with competitors like electronics chain Best Buy Co. (BBY) and book sellers like Borders Group Inc. (BGP) and Barnes & Noble Inc. (BKS), which are required to collect sales taxes by virtue of their physical presence in states across the country.

He said the effect on Amazon's sales would be of "modest magnitude" given that after-tax prices would increase by about 7%, assuming the retailer passed the entire cost of taxes to consumers.

"People are sufficiently comfortable with online shopping that they do not need a sales tax subsidy to shop online," said Fox.

Amazon spokeswoman Patty Smith declined to speculate on how collecting sales tax would impact the company's business. But she noted the retailer currently collects tax in several states, such as North Dakota, Kentucky and Washington, where it maintains "a thriving business."

Amazon has said it would support a federal effort to streamline state tax laws and give signatory states the authority to require all sellers to collect taxes, regardless of whether they are physically present in those states.

"We'd be O.K. with a sales tax collection requirement under a system that is as simple as the current physical presence-based system and is evenly applied to all sellers," said Smith.

Last year, Amazon started collecting taxes in New York after the state passed a law requiring the company to do so. Amazon fought the law in court and lost, but the company is appealing that decision.

Amazon shares, up almost 55% for the year, gained $1.59, to $79.27 on Wednesday.

-By Scott Morrison; Dow Jones Newswires; 415-765-6118; scott.morrison@dowjones.com