WASHINGTON, DC - JUNE 24: (L to R) Allen Kane, Director of the National Postal Museum, Chris Karpenko, Executive Director, Brand Marketing, United States Postal Service, and Sharon Cohen, Executive Vice President, Partnership Marketing, Nickelodeon, at the SpongeBob Mailbox induction ceremony at the Smithsonian National Postal Museum on June 24, 2016 in Washington, DC. (Photo by Paul Morigi/Getty Images for Nickelodeon)

WASHINGTON, DC - JUNE 24: (L to R) Chris Karpenko, Executive Director, Brand Marketing, United States Postal Service, SpongeBob SquarePants, Allen Kane, Director of the National Postal Museum, and Sharon Cohen, Executive Vice President, Partnership Marketing, Nickelodeon, attend the SpongeBob Mailbox induction ceremony at the Smithsonian National Postal Museum on June 24, 2016 in Washington, DC. (Photo by Paul Morigi/Getty Images for Nickelodeon)

WASHINGTON, DC - JUNE 24: House Ways and Means Committee Chairman Kevin Brady (R-TX) introduces the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: House Ways and Means Committee Chairman Kevin Brady (R-TX) (R) introduces the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) (C) addresses a news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: House Ways and Means Committee Chairman Kevin Brady (R-TX) (R), Speaker of the House Paul Ryan (R-WI) (L) and House Majority Whip Steve Scalise (R-LA) address a news conference to introduce the House Republicans' tax reform proposal with in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: Speaker of the House Paul Ryan (R-WI) speaks during news conference to introduce the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. House Ways and Means Committee Chairman Kevin Brady (R-TX) said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 24: House Ways and Means Committee Chairman Kevin Brady (R-TX) introduces the House Republicans' tax reform proposal in the Rayburn Room at the U.S. Capitol June 24, 2016 in Washington, DC. Brady said that the GOP wants to 'bust up' the Internal Revenue Service, get rid of the estate tax and create a tax code so simple that Americans can file on a postcard-sized form. (Photo by Chip Somodevilla/Getty Images)