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I've been offered a return offer for a summer internship at a firm in a different country than the one I reside in. I would love to return, but salaries there are significantly lower than the country living I live in, to the degree that internships typically pay 2-4 times what they are offering.
I may move to this country in a few years and would like to get a job with this company if I do. The salary they are offering is very competitive there, just not here.
Should I explain to the company that I am rejecting their offer for financial reasons? On the one hand, I want them to know that it's not for any negative reason and I would like to continue with them later on. On the other hand, I'm afraid that this sounds unprofessional and may offend them.
Note that this is a small firm and the managers will definitely remember me later on.