It's not amortized. I.e. the company simply subtracts all salaries for the year from the revenue and pays tax from the difference. Salaries being amortized means on year 1 you can only subtract X% of salaries and the taxable amount becomes much larger. Year 2 you will use the X% for the second year salary and another Y% for the already paid salary of the first year. So, the difference becomes less, and the taxes become less, too.

For a stable company that has a constant revenue stream and an established body of workers there's no much of a difference: instead of paying all tax for current year salary you pay 6 chunks of tax for 6 different years of salaries - which would be about the same amount.

For early companies things can be pretty tough. You may earn, say 100k in a year one and pay your employee 100k. Your company now has 0 in the bank, but for the taxation purposes the taxable amount is like (100k - 10% of 100k = 90k), at 20% corporate tax that would mean that the company has 0 in the bank but owes the government $18k in taxes. It's much harder to start a software business in this kind of environment.

In Sweden you have the option to capitalize software development costs, under some specific circumstances, but in general you would expense such costs immediately.

Some startups do it to window-dress their balance sheet, though. But making it compulsory is absurd.