Random Musings wrote:MAP-21' which was part of a transportation bill
The reason pensions are part of MAP-21 is because the law was intended to be "revenue-neutral". That is, government spending had to be exactly offset by government savings.
Congress saw a way to get pension plan sponsors to temporarily pay more in taxes -- by temporarily reducing the tax deductible amounts they were required to contribute to qualified pension plans. Their method for doing so involved stipulating that the interest rates used for determining target liabilities be within a corridor around 25-year average interest rates. The corridor starts out narrow -- hence has the immediate effect of reducing funding requirements. However, the corridor quickly widens over subsequent years, so the impact of the 25-year average goes away.
Within a short period of time (barring passage of other laws) you'll be back to what you're used to seeing.