The deficit hawks have routinely included legislation that included automatic ways to reduce the US deficit to be implemented at a future point in time, when hopefully Congress has sorted out whether or not such a thing is actually desirable. It's essentially a budget Sword of Damocles.

Of course, Congressional budget negotiations have been an unproductive circus show for a while, so this never actually happened and the thing that was never actually intended to go in place went in effect. With the current razor-thin majority in the House constantly getting derailed over budget negotiations, this is unlikely to resolve any time soon.

The change was part of the trump tax bill, which at least needed to be able to claim that it was revenue-neutral after 10 years to be able to be passed through the budget reconciliation process.

You have chunks of the explanation in other responses, let's try to put them together:

Since Obama became president, all legislation basically needs 2/3rds of the senate to pass if it's remotely controversial and every tax change is controversial. There is one exception though: if the bill is of a budgetary nature, and is revenue neutral over 10 years.

Trump really wanted to pass some tax cuts in 2017. But as you'd expect, claiming that a big tax cut is revenue neutral is far more than the senate parlamentarian would believe. So instead, some tax cuts are made temporary, and some tax changes are made that would gain revenue. Then the whole thing appears to be revenue neutral over a decade, because nobody expects that the poison pills at the end will actually be allowed to happen. They tend to come in 6+ years later, as to make sure that all senators and the president might also claim said increases are not their problem.

So the expectation is that a future congress will just undo those tax changes, and push them further into the future, by again making another bill that looks revenue neutral in the long run, but is just kicking the ball down the road.

The congress since the midterms, however, is even less functional than in the Obama or Trump years: So the poison pills that are not supposed to happen are starting to happen. Other cuts that occurred, like the increase of the standard deduction, were also marked as temporary, and could come back if congress doesn't do anything.

So ultimately it's all side-effects of people trying to bypass congressional rules, because otherwise we'd not see anything other than emergency spending bills passing in congress. Changes to legislation that would make this kind of dysfunction stop happening are even harder to pass. Every incentive pushes politicians of all parties to play with fire. This time we got burned.

https://blog.pragmaticengineer.com/section-174/ is a good overview and describes some of the history:

> In 2017, then-President, Donald Trump, signed the 2017 Tax Cuts & Jobs act, which overhauled tax codes and reduced tax – for example, it reduced the top tax bracket from 39.6% to 37%. To make the bill pass strict budgetary rules, the Senate used a process called reconciliation: adding in tax code changes that delayed tax increases. These delayed increases “balanced out” the tax reduction.

> One of these changes was Section 174, set to come into effect 5 years later, in 2022. These parts deliver the blow by making it clear that software development costs need to be amortized over 5-15 years. Most experts expected Congress to push back the Section 174 amendment to a later date, or simply remove it. But Congressional negotiations to repeal the changes fell apart at the last minute in December 2022, meaning it became law.

> Amazon, Microsoft, Intel, Ford, Lockheed Martin, and other US companies created the US R&D Coalition in 2018 to advocate in reversing this change. This group concludes... "By diminishing the near-term value of R&D expenditures, the Tax Cuts and Jobs Act will reduce incentives for companies to invest in the development of new products, ultimately hurting consumers and businesses alike.”

> What about VC-funded companies? For loss-making companies this change doesn’t make much of a difference. But the change does impact VC-funded companies near to break even. Most VC-funded companies close to breakeven have big-enough cash buffers with which to pay unexpected tax bills. However, these companies might reduce hiring – or even consider letting go staff.

My 2c are that big tech companies with large amounts of cash on hand wanted to be seen optically as fighting against this change... but those with cash on hand would also benefit from being the only ones able to weather the storm relative to their would-be competitors. It's unclear that incentives were aligned here among those companies with lobbying budgets.

Anything that pulls in income and/or pushes out expenses results in a higher tax liability to the IRS. It makes a lot of sense in the world of real estate and equipment expenses (i.e. items which have very long useful lives to a business), less so for labor and other short term expenses.

I'm not an accountant, but to me it looks like the IRS was operating at an assumption that the software engineers write is not immediately consumed, but rather has on average 5 years amortization period (meaning, it's producing value for 5 years, on average).

Same reason why the Trump Tax cuts almost made PhD tuition waivers taxable.

1) Tech workers are liberals

2) Liberals being owned is good if you're an administration consumed with punishing your enemies and enriching your allies

#2 is also why SALT deduction was curtailed, to punish blue states. While I think that's accidentally good policy, it made people mad enough to flip the House in 2018.