With Medtronic's $43 billion acquisition of Covidien, Pfizer's failed $119 billion bid for AstraZeneca, and AbbVie's pending $46 billion proposal for Shire, conflicting opinions abound about the merits and drawbacks of tax inversions. Some consider them unpatriotic. Others believe companies are bound by fiduciary responsibility to consider them.

My conclusion: Companies that do deals primarily driven by tax considerations are headed for trouble. This lets the tail wag the dog. The only justification for a merger or acquisition is to strengthen your company's strategic position. That's what motivated Medtronic CEO Omar Ishrak to pursue the Covidien acquisition: The companies fit together perfectly.

Here are five tests that boards of directors should satisfy before approving any deal:

Does the acquisition further your company's mission? Your mission should provide purpose beyond financial returns that creates value for customers, employees, shareholders and other stakeholders. Most important, it should motivate employees to create innovations and deliver great service far more than financial incentives.

Does it advance your global strategy? If companies want to expand into higher growth markets, acquisitions can accelerate their growth. If its strategy is emerging market growth, acquisitions can provide greater presence. Sound acquisitions can also strengthen new-product pipelines.

Does it motivate your employees and the acquired company's? Sustained value creation only occurs through dedicated employees working together to advance the company's mission. The key is to engage employees of the newly acquired company to commit to their new owner. That's what Medtronic did a decade ago with its acquisitions of Sofamor-Danek, AVE, and Mini-Med, as employment tripled. Acquisitions also create personal growth opportunities for current employees.

Will the acquisition lead to sustainable earnings growth? The acquisition should be accretive to earnings within two years, including realistic cost-saving synergies, without cutting back investments in future growth. Acquisitions like Valeant's proposed hostile takeover of Allergan, which is based on cutting R&D spending from 17 percent of revenue to 3 percent, fail to produce sustainable earnings growth.

Pfizer erred in betting entirely on cost cuts to justify $240 billion it spent to acquire Warner-Lambert, Pharmacia-Upjohn and Wyeth. As a result, its shareholder value declined 32 percent in 14 years. In its failed bid to acquire AstraZeneca, the latter's shareholders were extremely wary of Pfizer's tactics.

Can the acquisition be funded without putting your balance sheet at risk? Successful acquisitions must generate future cash flow to repay the investment. These days borrowing money is cheap due to low interest rates, but companies shouldn't get overleveraged in case of economic downturns, as they did in 2008-09.

What about taxes?

Taxes are the No. 1 question on everyone's mind with Medtronic's acquisition. After the company answered the first five questions affirmatively, it sought ways to finance it utilizing $14 billion in trapped cash. The tax inversion gave Medtronic access to these funds and also $7 billion in annual cash flow after the acquisition closes.

Do companies have an obligation to repatriate overseas earnings and pay the additional 35 percent in U.S. taxes? Not in the opinion of CEOs and CFOs. That's why U.S.-based corporations are keeping foreign earnings abroad, leaving over $2 trillion in cash trapped overseas.

The U.S. already has the highest corporate tax rate in the world, which is a significant competitive disadvantage to U.S.-based global companies. To access overseas cash, even for domestic investments, there is a significant incentive for tax headquarters to migrate abroad. The ideal solution is for Congress to rewrite the corporate tax code. But given the stalemate that currently exists in Washington, a tax bill is highly unlikely before 2017.

In the near term, President Obama should declare a six- to 12-month "repatriation holiday," enabling companies to bring cash home tax-free provided they present plans to reinvest the funds in capital expenditures, R&D, job creation and new ventures. I have recommended this approach since 2010. So far, nothing has happened. As a consequence, U.S. companies are finding alternative approaches such as tax inversions. Otherwise, they are in the unenviable position of being worth more to a foreign buyer than to their own shareholders.

Bottom line: Tax inversions should only be considered after the first five tests are answered satisfactorily.

Bill George is professor of management practice at Harvard Business School, author of "True North" and former chairman and CEO of Medtronic.