If I hire a bunch of people to build me an apartment building, I deduct the full cost of their salaries in the year I pay them, even though once they build the apartment building, I get the value of that work over the following years.
How is that any different from hiring a bunch of people to write some software, that I then get the value of over the following years?
> If I hire a bunch of people to build me an apartment building, I deduct the full cost of their salaries in the year I pay them
That’s not how it works in general (there are exceptions though): https://www.law.cornell.edu/cfr/text/26/1.263A-1