March 14, 2026
XML is back—and so is the drama
XML Is a Cheap DSL
IRS open-sources tax tool and sparks XML vs JSON brawl
TLDR: The IRS launched a free, open-source tax estimator built on XML rules. Devs split fast: fans praise XML’s built-in checks and clarity, skeptics slam parsing costs and maintenance, and jokesters hunt tax-code loops—big deal because public code needs readable, trustworthy rules everyone can scrutinize.
The IRS just dropped a free, open-source Tax Withholding Estimator, and the internet immediately turned it into a cage match over XML—yes, that old-school markup language you remember from enterprise nightmares. The tool models tax rules in human-readable XML to figure out what you owe or get back, and the dev who helped build it says XML still slaps for clear, cross-platform rulebooks. Cue: comment-section fireworks.
On one side, the anti-XML crowd rolled in with a hangover from the early 2000s. “It’s not cheap,” warned one voice, pointing to the mental load and maintenance. Another piled on with performance worries: XML is “notoriously expensive to properly parse,” and real compatibility hangs on a few creaky libraries. Meanwhile, the pro-XML squad showed up waving schema flags—built-in rule checks that catch mistakes fast. As one fan put it, if you use the right tools, XML is “the right tool for a majority of jobs.” A spicy history lesson popped up too: one commenter argued today’s web tooling exists largely because XML lost the browser war to JSON, even though XML already solved problems devs had to bolt onto JSON later.
And of course, the memes: someone joked there are “cycles” in the tax code for infinite taxes or zero taxes—“can AI find them?” Devs are split, the jokes are flying, and XML is somehow the main character again. Popcorn time. XML
Key Points
- •The IRS released a new free, open-source Tax Withholding Estimator (TWE) and opened it to public contributions.
- •TWE is a static site generated from XML configurations, including a Fact Dictionary representing the US Tax Code.
- •A logic engine called Fact Graph computes tax obligations using XML-defined facts and operators.
- •The Fact Graph was originally developed for IRS Direct File and is now used in TWE.
- •Examples demonstrate XML encoding of calculations for total owed, refundable credits, and non-refundable credits (with a cap at zero).