In the Senate specifically you need 60 votes to break a filibuster. Filibustering, if we Americans remember from Civics/US Govt class in high school, happens when a senator exercises their right to speak for as long as they wish. Or at least it used to. There was a rule change a few decades ago to allow something called a “pocket filibuster” where you don’t have to keep speaking but you can block further motions on the matter. This requires at least 60 votes to break, so it’s effectively impossible to do anything in the Senate without that many votes now.
There were some legendary filibusters back in the day. One famous example was when Strom Thurmond filibustered the Civil Rights act by speaking for 24 hours continuously. He was not able to block the bill by continuing to speak because there are limits to how long someone is able to stand and deliver, and originally if you stopped speaking you had to yield the floor and allow business to proceed.
Republicans supported the repeal, so 60 votes in the Senate were possible if the Dems wanted to repeal it. They didn't want to, coz they passed two reconciliation bills with zero republican votes and could've included the repeal in either one of them. Their policy is explicitly to tax corporations more. They didn't even let the clean repeal bills have a vote.
It has been a common tactic to work around the filibuster and reconciliation rules, and to repeal them later. They didn't expect the democrats to oppose the repeal so hard and destroy tech jobs on their watch. They know no one will ever blame them for it, like you can see on HN. Democrats platform is all about higher taxes on corps so that tracks with their actions, jobs be damned.
The point is that you don't need 60 votes to break a filibuster to increase or decrease taxes or make any other budget related changes in a once-a-year budget bill called the reconciliation bill. You just need a simple majority of 51 votes(or 50 plus VP to break the tie like the dems had).
This process was used several times to pass key and major bills like the Inflation Reduction Act, Trump's tax bill in 2017, the big beautiful bill last month etc.
Dems did not need 60 votes to restore the R&D exemption changes. They could've just included it in the reconciliation bills they passed with just 50 votes because it qualifies as a budgetary change. That's exactly how the Republicans got it done recently after getting back in power, with zero Dem votes for this change.
You completely missed that in your comment so I was trying to add some information.
There were some legendary filibusters back in the day. One famous example was when Strom Thurmond filibustered the Civil Rights act by speaking for 24 hours continuously. He was not able to block the bill by continuing to speak because there are limits to how long someone is able to stand and deliver, and originally if you stopped speaking you had to yield the floor and allow business to proceed.