A few months back, ProPublica's director of research, Liz Day, started to notice similar language in op-eds and letters opposing return-free tax filing, a little-known proposal that would give taxpayers the option to use pre-filled tax returns to save time and money. She joined Assistant Managing Editor Eric Umansky in the Storage Closet Studio to talk about what she found when she started investigating.

It turns out, the letters sounded alike because the signers were often getting their information -- and indeed, the form letters and op-eds themselves -- from lobbyists and public relations professionals with connections to the Computer & Communications Industry Association, a trade group that counts Intuit -- the maker of Turbo Tax -- among its members. (It's not the first time she's investigated Intuit's actions against proposals that would undermine its business; see her 2013 story on how the company has lobbied on federal bills on return-free filing and fought a version of pre-filled returns in the company's home state of California.)

Strikingly, some of the letter writers Day contacted were unaware of the industry forces behind the scenes.

"It's not the most natural thing to point out that someone might not have done their own independent research," Day says. Some of the op-eds and letters, she added, made claims she had trouble verifying, including one that return-free filing would end tax-prep assistance that the government gives to low-income communities. 

To be clear, Umanksy points out, "There's nothing necessarily wrong with the idea" of targeting community leaders and local influencers on a cause -- "grasstopping," in industry lingo -- "if you are transparent, and giving accurate information, both of which were not the case in multiple instances."

Listen to the podcast for the full behind-the-scenes look at Day's article. You can hear it on SoundCloud, iTunes and Stitcher.