Consider a scenario where Amazon.com Inc. is planning to invest $1.5 billion in research and development (R&D) initiatives over the next three years. According to the company's financial projections, the expected annual qualified R&D expenditure is $500 million. Estimate the potential tax benefits for Amazon from claiming the research and development tax credit, which is 20% of qualified R&D expenditures. Calculate the net tax savings over the three-year period, taking into account the corporate tax rate of 21% and any applicable limitations on the R&D tax credit.