Talking about money is not rude. It is a normal part of agreeing to work. But there is a way to do it that leaves you better off.
Before the interview, learn the market. Ask people working in the same field, or look at similar adverts and see what they pay. You want two numbers in your head: what you are hoping for, and the lowest you would accept. Know them before you walk in.
When they ask what you expect:
- Give a range rather than a single figure. "Between X and Y, depending on the full responsibilities."
- Make the bottom of that range a number you would genuinely be happy with, because that is usually the one they hear.
- If they ask early, before you understand the job, it is fine to say: "Could I understand the responsibilities a little better first?" That is normal and accepted.
When they make an offer:
- Do not say yes on the spot. Thank them and ask for a day to think. That is your right and no reasonable employer minds.
- Salary is not everything. Ask about health cover, hours, leave, whether you can work from home, whether there is training. Sometimes those are worth more than a small difference in the figure.
- If the number is below what you expected, you can negotiate once, politely: "I am very interested in the role, but I was expecting around X, based on my experience in Y. Is there room?" The worst that happens is they say no.
One thing that matters: get whatever you agreed in writing, in an offer or a contract, before you leave your current job. Spoken agreements get forgotten. Written ones do not.