How to politely inform I am not interested in a tentative full time offer from supervisor after internship?

Question

I'm currently interning at a company A and my supervisor asked if I would be interested to continue working here. The conversation mainly consisted of him discussing with me if I would be interested in learning some new skills I would need to develop for the projects I would work on in my full-time job, what I am interested in working on, also some technical questions. I say conversation, although it felt like an interview as it happened out of the blue (we had been discussing about the end date of my internship a few hours before this conversation occurred but even then there were no hints a full time job was available).

I said I was interested and discussed mainly the skills I would need to develop but didn't ask for the specifics like the salary as a) he said it was a tentative offer, and that there might be other applicants, b) I was also interviewing with company B at the time and c) I would like to work there if I didn't get the job at company B. I asked him if I could speak to him about it again in a month, but I didn't mention about interviewing with other companies (he might have guessed, obviously).

While my supervisor and the team are amazing (I've learned a lot here and they're all really nice), I got an offer from company B whose work I'm more interested in (the domain is different) so I'm planning to accept that.

While it wasn't a formal job offer, it is still my responsibility to tell him I am not interested as I had previously expressed interest and I don't want to burn any bridges. I know I'm not irreplaceable and its not a big deal but I would like to maintain a positive relationship with him even after I leave the company. What would be a polite way of telling my supervisor that I really appreciate the offer but I will not continue here/am not interested in the full time offer?

Answer 1

it is still my responsibility to tell him I am not interested as I had previously expressed interest and I don't want to burn any bridges.

Yes. In this case this is just common courtesy and being open and proactive will minimize any potential damage. It's easy enough:

Hey boss, we discussed a potential job after my internship. I've given this some real thought and I've come to conclusion that I want to work somewhere else. I'm having a really good time her, and I'm very grateful the opportunity and all the learning, but my domain interest is really somewhere else. I just wanted to let you know.

The earlier you tell your boss the quicker they can focus on different candidates. The longer you wait the more your boss might get invested in the idea.

However, make sure that the offer from company B is "in the bag" first.

Answer 2

The problem is, you already told him you were interested, so declining one in advance is a bit troublesome.

I would let it be. After all they may not make an offer. Also if they do make an offer and all others fall through would you take it? What are you going to do if no offers are forthcoming?

It sounds like you are a bit confused yourself and perhaps some clarity will help you make a decision. Who, of the companies you are interviewing with actually extend an offer? Who will offer what pay? Once you have that info it will be easier to make a decision.

So I would keep it to yourself for now.