Our nation very much needs fundamental tax reform, so it’s welcome news that major public figures – including presidential candidates – are proposing to gut the internal revenue code and replace it with plans that collect revenue in less-destructive ways.

A few months ago, I wrote about a sweeping proposal by Senator Marco Rubio of Florida.

Today, let’s look at the plan that Senator Rand Paul has put forward in a Wall Street Journal column.

He has some great info on why the current tax system is a corrupt mess.

From 2001 until 2010, there were at least 4,430 changes to tax laws—an average of one “fix” a day—always promising more fairness, more simplicity or more growth stimulants. And every year the Internal Revenue Code grows absurdly more incomprehensible, as if it were designed as a jobs program for accountants, IRS agents and tax attorneys.

And he explains that punitive tax policy helps explain why our economy has been under-performing.

…redistribution policies have led to rising income inequality and negative income gains for families. …We are already at least $2 trillion behind where we should be with a normal recovery; the growth gap widens every month.

So what’s his proposal?

…repeal the entire IRS tax code—more than 70,000 pages—and replace it with a low, broad-based tax of 14.5% on individuals and businesses. I would eliminate nearly every special-interest loophole. The plan also eliminates the payroll tax on workers and several federal taxes outright, including gift and estate taxes, telephone taxes, and all duties and tariffs. I call this “The Fair and Flat Tax.” …establish a 14.5% flat-rate tax applied equally to all personal income, including wages, salaries, dividends, capital gains, rents and interest. All deductions except for a mortgage and charities would be eliminated. The first $50,000 of income for a family of four would not be taxed. For low-income working families, the plan would retain the earned-income tax credit.

Kudos to Senator Paul. This type of tax system would be far less destructive than the current system.

That being said, it’s not perfect. Here are three things I don’t like.

The Social Security payroll tax already is a flat tax, so it’s unclear why it should be wrapped into reform of the income tax, particularly if that changecomplicates the possibility of shifting to a system of personal retirement accounts. There would still be some double taxation of dividends, capital gains, and interest, though thedestructive impact of that policywould be mitigated because of the low 14.5 percent rate. The earned-income credit (a spending program embedded in the tax code) should be eliminated as part of a plan to shift all means-tested programs back to the states.

But it’s important not to make the perfect the enemy of the good, particularly since the debate in Washington so often is about bad ideas and worse ideas.

So the aforementioned three complaints don’t cause me much heartburn.

But there’s another part of the Paul plan that does give me gastro-intestinal discomfort. Here’s a final excerpt from his column.

I would also apply this uniform 14.5% business-activity tax on all companies…. This tax would be levied on revenues minus allowable expenses, such as the purchase of parts, computers and office equipment. All capital purchases would be immediately expensed, ending complicated depreciation schedules.

You may be wondering why this passage is worrisome. After all, it’s great news that the very high corporate tax rate is being replaced by a low-rate system. Replacing depreciation with expensing also is a huge step in the right direction.

So what’s not to like?

The answer is that Senator Paul’s “business-activity tax” doesn’t allow a deduction for wages and salaries. This means, for all intents and purposes, that he is turning the corporate income tax into a value-added tax (VAT).

In theory, this is a good step. After all, the VAT is a consumption-based tax which does far less damage to the economy, on a per-dollar-collected basis, than the corporate income tax.

But theoretical appeal isn’t the same as real-world impact.

Simply stated, the VAT is a money machine for big government.

All of which helps to explain why it would be a big mistake to give politicians this new source of revenue.

Indeed, this is why I was critical of Herman Cain’s 9-9-9 plan four years ago.

It’s why I’ve been leery of Congressman Paul Ryan’s otherwise very admirableRoadmap plan.

And it’s one of the reasons why I feared Mitt Romney’s policies would have facilitated a larger burden of government.

These politicians may have had their hearts in the right place and wanted to use the VAT to finance pro-growth tax reforms. But I can’t stop worrying about what happens when politicians with bad motives get control.

Particularly when there are safer ways of achieving the same objectives.

Here’s some of what I wrote last year on this exact topic.

…the corporate income tax is a self-inflicted wound to American prosperity, but allow me to point out that incremental reform is a far simpler – and far safer – way of dealing with the biggest warts plaguing the current system. Lowerthe corporate tax rate. Replace depreciation with expensing. Replace worldwide taxation with territorial taxation. So here’s the bottom line. If there’s enough support in Congress to get rid of the corporate income tax and impose a VAT, that means there’s also enough support to implement these incremental reforms. There’s a risk, to be sure, that future politicians will undo these reforms. But the adverse consequences of that outcome are far lower than the catastrophic consequences of future politicians using a VAT to turn America into France.

To wrap things up, there’s no doubt that Senator Paul has a very good proposal. And I know his heart is in the right place.

But watch this video to understand why his proposal has a very big wart that needs to be excised.

For what it’s worth, I’m mystified why pro-growth policy makers don’t simply latch onto an unadulterated flat tax.

That plan has all the good features needed for tax reform without any of the dangers associated with a VAT.

P.S. You can enjoy some good VAT cartoons by clicking here, here, and here.