The Delaware Chancery court has rejected the contention that there is an independent duty of directors and officers to minimise taxes payable by the corporation (or framed in another way, that it would be wasting corporate assets not to do so): Seinfeld v Slager (Del. Ch. 29 June 2012).
The correct view is that there can’t be such a duty, because there may be a variety of reasons why a company may or may not choose to take advantage of tax-planning opportunities. This is a decision best left to the business judgment of management. While overpayment of taxes could conceivably be a breach of fiduciary duty, there is no freestanding duty to minimise taxes, and failure to do so is not automatically a waste of corporate assets.