As a newly admitted student in PhD program, I have been awarded TA ship by my department for academic year Fall 2020-spring 2021. the stipend is quite generous that is 2300usd/month. In funding letter they have mentioned TA award for first academic year and for the rest of my studies it is only mentioned that they are committed to provide funding support. so i wanted to ask if it is usual that the program only provide detail funding info for first year? or they do provide full funding details (mentioning of awards) for all 4 years?
Most places run on one year budget cycles so a commitment beyond one year would be hard to assure. But unless the educational system falls apart and there are no students to teach, getting a renewal would be assumed. Of course you need to do a good job also to get a continuation of a TA. But research institutions couldn't really run without lots of TAs in some fields.
But they make a "promise" to provide funding. You can expect best efforts on their part but it isn't an absolute guarantee.
In the US, in particular, State Universities are subject to budget constraints made by the legislature. They just have to deal with it.