Well, Barbie did say that "math is hard!"
A surcharge of 0.9% on a 5% tax base is an 18% tax increase. I don't know if the politicians are unable to do simple math or if they depend on the fact that many people are innumerate and unable to catch their lies.
As for "temporary" taxes, we're still paying taxes for the Spanish-American War over 100 years after it ended. We're still living under an income tax that was expanded from being a "tax on the rich" to pay for World War I. We're still paying excise taxes that were passed in WWII for specific reasons that no longer exist.