Final answer:
It is true that all long-term capital gains and qualified dividends must be included in net investment income when electing to do so for tax purposes, as this affects the calculation of taxes and can influence economic growth.
Step-by-step explanation:
The statement is True. When electing to include long-term capital gains and qualified dividends in net investment income, taxpayers must include all long-term capital gains and dividends recognized for that year. When you decide to include these gains and dividends as a part of your net investment income for tax purposes, you cannot selectively include some while excluding others. This inclusion is critical when calculating the Net Investment Income Tax (NIIT) or considering other tax-related calculations. Investment gains can be a key factor in promoting economic growth, as low capital gains taxes can incentivize investment and savings, which in turn spur economic activity.