New U.S. tax rules are requiring companies to take extra care with timing and documentation when making loans and disbursements to related companies, lest regulators reclassify their tax-free deductible interest payments as taxable, nondeductible dividend payments.

While the regulations still only affect companies holding at least $100 million in assets or making $50 million a year, that may include some larger domestic and foreign investors who purchase U.S. real estate through corporations.