In the U.S., most salary jobs are spoken about in annual terms. Job listing's list annual salary, offer letters list annual pay, my employee portal lists annual pay, etc. My pay stubs are biweekly though. Pretty much nothing is ever described in monthly terms, at least not that I've ever seen.

Same in Croatia. Also think it's in most countries.

Are you taxed based on your yearly income, or month by month?

At least in Germany, depending on contract, monthly payments vary heavily. For instance the labour agreement for the automotive industry contains a 13th salary at christmas time, vacation pay in summer, a bonus in spring depending on company performance, a potential bonus if you pass on some vacation days and more. Other contracts only have a monthly salary and no bonuses. My contract has only one bonus depending on company performance in April while my wife gets 12.8 monthly salaries (1.8x salary in November as end-of-year bonus). To compare job offers in any way, you can only go with the annual number.

In NZ we would talk annual salary, rent per week, and we just don't talk about mortgage payments because it's easier not to.

I think we probably do annual salary because there isn't consistency with how people are paid. Weekly and fortnightly are probably the most common, but monthly is pretty normal too and I've seen some being paid twice monthly.

It makes sense... until you learn about the 13th/14th month of the year. Having to multiply the monthly salary by 13.x (depending on the collective agreement of course) to get the taxable income makes imperial measurements sound logical.

Give me yearly or give me hourly, but monthly makes no sense under the current system.