Warren Buffett says Congress should enact a law establishing a minimum tax rate on the wealthy right now.

In an op-ed piece for The New York Times, Buffett disputes the claim that higher tax rates on the rich discourages investment. “Between 1951 and 1954, when the capital gains rate was 25 percent and marginal rates on dividends reached 91 percent in extreme cases, I sold securities and did pretty well,” Buffett says. “In the years from 1956 to 1969, the top marginal rate fell modestly, but was still a lofty 70 percent — and the tax rate on capital gains inched up to 27.5 percent. I was managing funds for investors then. Never did anyone mention taxes as a reason to forgo an investment opportunity that I offered.”

“Let’s forget about the rich and ultrarich going on strike and stuffing their ample funds under their mattresses if — gasp — capital gains rates and ordinary income rates are increased,” Buffett says. “The ultrarich, including me, will forever pursue investment opportunities.”

Buffett says broader changes need to be made to the tax code, but he says Congress shouldn’t wait to establish a minimum tax on the wealthy. “The [broader] reform of such complexities should not promote delay in our correcting simple and expensive inequities,” he says. “We can’t let those who want to protect the privileged get away with insisting that we do nothing until we can do everything.”