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I'm working as a software developer in a company doing product R&D consulting. I've been here for 10 months and it's my first full-time job after graduating with a Masters last year. For various reasons, I have started to consider pursuing a PhD, starting in the Autumn of next year.
I am pretty sure I want to communicate this desire to my employer for several reasons:
Honesty - they are investing in me in the form of training and knowing I might leave might alter their desire to do so;
Letters of recommendation - I will definitely want my employer's assistance in getting into a desired programme, probably in a form of a letter of recommendation. I am on very good terms with my manager and technical lead so in general I don't think there would be any problems with asking them for that;
"Returnability" - because of the R in the R&D of my company (and because plainly my company a great place to work), I can see being seriously interested in coming back here in a different role after being done with my PhD (or if I change my mind during it).Thus I want to keep friendly relations with the company and not just pull off a surprise quit on them.
What I'm not sure about is when would be a good time to communicate this potential plan of mine to the employer. On one hand keeping this thought to myself makes me feel dishonest, on the other hand I'm concerned that once I make my intention clear, even if it's not certain, my career will stop (no more training, no more interesting projects etc.).
So hence the question: When should I communicate this thought of mine and should I be mindful of anything I haven't considered yet when I do it?