Social Security benefits first became partially taxable in 1983, and the rule was expanded in 1993 to its current form. As the rules stand now, rising income can subject 50% or even 85% of Social Security benefits to taxation, until a maximum of 85% of all Social Security benefits are included in income for tax purposes.
The reason the taxability of Social Security matters is not just that it raises a client's tax burden in the aggregate, but that it can boost a client's marginal tax rate far above the tax bracket alone; those in the 15% tax bracket may actually face marginal rates of 22.5% to 27.75%, and those in the 25% tax bracket can see marginal tax rates spike as high as 46.25%!
Fortunately, this rate eventually reaches a cap - when the maximum amount of Social Security benefits are being taxed - and the client's tax rate returns to normal. Nonetheless, while clients are going through the income levels where Social Security phases in - which can begin with as little as $25,000 of income for individuals - tax rates rise high enough that more proactive tax planning, from Roth conversions to the use of annuities and asset location strategies, becomes crucial to manage a client's overall tax exposure!