Watch Ivanka Try (& Fail) To Explain Taxes In This Painful Video

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Following passage of the GOP's tax bill that she worked behind the scenes to promote, the first daughter made a major blunder while speaking on the issue. Quotes from Thursday morning interview with Fox & Friends insinuated that the tax reform would effect Americans' 2017 taxes and that taxpayers' filing would fit on a postcard, giving the impression that Ivanka Trump doesn't understand how taxes are filed.

"I'm really looking forward to doing a lot of traveling in April when people realize the effect that this has," she said in an interview with Fox News. "The vast majority will be [doing their taxes] on a single postcard." However, during her travels across the country, what Trump will witness will actually be the effects of the previous tax code, because Americans will file their 2017 taxes in April.

Though the president is expected to sign the GOP tax bill into law in early January, much of the bill won't take effect until the following year. As Fortune's John Patrick Pullen explains, people will see "some benefits like lower tax withholding" in April, but "other perks won't show until you file your tax return in April 2019."

The first daughter's comment about people filing their taxes "on a single postcard," also didn't make a whole lot of sense, considering that's not how taxes are filed.

GOP leaders have long called for the American tax code to be simplified, and while celebrating the new bill Wednesday, House Speaker Paul Ryan told NBC News:

We're making it so simple that almost nine out of 10 taxpayers can do their taxes on a form like a postcard.

The president touted the same idea back in November, before the bill was finalized. He even went so far as to kiss a postcard-sized piece of paper to show his affection for simplified tax reform. The first daughter's Thursday interview signals that she picked up the postcard language, but anyone who's ever filed taxes knows fitting everything on a single postcard would be a major feat.

Unfortunately for Ryan and Trump, the GOP tax plan doesn't quite accomplish that goal. The New York Times' Jim Tankersley explains why the reform still doesn't pass the "postcard test":

It leaves nearly every large tax break in place. It creates as many new preferences for special interests as it gets rid of. It will keep corporate accountants busy for years to come. And no taxpayer will ever see the postcard-size tax return that President Trump laid a kiss on in November as Republican leaders launched their tax overhaul effort.

Following Trump's on-air gaffe, people on Twitter roasted Trump for not understanding how taxes work. (After all, she played a big role in pushing the tax reform through Congress — so she ought to know how average Americans file their taxes every year.) Some took her comments as a sign that she's never filed her own taxes, while others were intrigued by the April tour Trump mentioned, wondering who she'll bring along to witness the alleged tax postcards.

On top of her false postcard claim, Trump has also promoted the tax bill as a victory for middle-class families, even though analysis suggests otherwise. She championed doubling the child tax credit, which will have a minimal impact on most families, largely because it's not fully refundable and is coupled with the removal of the personal exemption. Most individual income tax provisions will also expire in 2025, forcing taxes to increase for more than half of U.S. households while reductions in corporate taxes are permanent.

Nevertheless, Trump and GOP leaders continue their victory lap celebrating the president's first major legislative win.