Do they buy drill presses or SUVs before the end of the year to take advantage of the current deduction, or wait to see what the new year brings?
Ramifications for the broader economy go beyond the boost from spending on equipment. If small-business owners have a better idea how much money they might save on their taxes, they might feel more secure and then expand and hire more workers. Small businesses employ about half the country's workforce, or about 60 million people.
Congress sometimes makes changes in the deduction retroactively. In January, lawmakers gave final approval to a bill that boosted the 2013 deduction to $500,000 from a planned $25,000 - after entrepreneurs had already made 2012 purchases based on the expected smaller deduction.
"People were making decisions they normally wouldn't be making at the end of last year," said Brian Burt, of the law firm Snell & Wilmer in Phoenix, whose clients include small businesses in manufacturing, financial services, and software.
The deduction allows small businesses to deduct up front the costs of vehicles, manufacturing equipment, furniture, and computers, meaning that tax savings come in the year the goods are purchased.
Without it, the businesses would have to depreciate the costs over a period of years that varies according to the type of equipment. Companies that get refunds get boosts in cash flow from tax savings.
"The Section 179 proposal is pretty big because it affects everybody," said John Arensmeyer, CEO of Small Business Majority, a group that lobbies on behalf of small businesses.
Camp, the House Ways and Means chairman, released what he called a bipartisan discussion draft of proposals to reform tax rules that affect small businesses, so the public could offer feedback. The Section 179 proposal is intended as part of an overhaul of the entire tax system.
Other suggestions in the draft include doubling the deduction for start-up costs.
Groups that lobby for small businesses say circulating the proposal publicly before it becomes a bill is a good move.
"This is the first time that I can recall when there's been a tax-reform discussion framed this way," said Todd McCracken, CEO of the National Small Business Association.