I am joining a new school as a TT Assistant Professor soon and I know I will be on the 'tenure clock' and have to publish manuscripts in certain prestigious journals. I have two pending publications in high quality journals that would certainly help a lot with this. In both, most of the research was done before I joined the new school, but will be published after I officially join.
- How do these papers get counted? Do they need the new affiliation in order to count towards tenure?
- Is it acceptable to change my affiliation to the new school?
There is substantial variation between universities, and to an extent departments within a university, about what counts towards tenure. The best way to find out is to ask your department chair, a mentor, or someone on the tenure and promotions committee about what counts.
That said, there are ethics regarding what affiliations should be listed on publications. If your "pending publications" are in press or far along the review process, it would be unethical to switch your affiliation. If you are still writing the manuscript, or the reviews require a major revision, and you do additional work while at your new university, then it would be appropriate to add an additional affiliation.