The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( Fisher Investments) -- It's an election year, which means we should all expect plenty of tax policy, debt and deficit rhetoric. And rhetoric can get heated -- but before getting swept away, here are some important factors to keep in mind. First, as we've written in the past, if put in context, the U.S.'s debt and deficit aren't as alarming as many fear. Our debt level has been relatively elevated lately, but our debt interest costs are low -- historically so.
Beyond worrying about just this year, though, an important question to ask is whether and how much tax policy really matters. Interestingly, through history, there's been enormous volatility in U.S. tax rates -- the top tax rate has been as high as 92% -- yet tax collection rates have never varied much as a percent of GDP, typically hovering somewhere between roughly 18% and 20%. Why would that be the case? Well, as the top rate increases toward 100%, folks who earn in that range are increasingly incentivized to minimize what they owe -- maybe some decide to work less, maybe some decide to spend more on tax preparation in order to find ways to reduce their taxable income, and so on. While a lower tax rate can be an incremental economic benefit, it's important to keep in mind tax rates are inherently a national issue, local to the U.S. -- but for stocks, global matters first and most. This is why the history of tax-rate moves and stock returns is mixed -- a tax hike isn't an automatic negative for stocks, nor is the reverse true. There are just too many other inputs in a fully globalized marketplace for any single factor to have that much influence. This election year (as with any other), everyone will no doubt have their opinions about what tax policy is best. But capital markets are incredibly complex -- it's critical to not overstate the impact of relatively marginal tax-rate moves.