should I tell my boss I'm leaving after my vacation?

A reader writes:

I have been with my employer for 1.5+ years, and at the start of this year I told them I was going to go to Europe in September. I booked my leave time, even though half of it is unpaid as I haven't accrued enough paid leave. This is all fine, and very nice of them to allow, but then I did give them 8 months notice!

In the last 6 months, however, I've become increasingly dissatisfied with my job. Eventually I made the decision that I wanted a new job, and about 3 months ago I put out some feelers about whether it was worth trying to find a new job, since I would need 8 weeks leave very quickly. A recruiter friend basically told me there was little point trying to find a new job since a new employer was unlikely to want to take me on with an 8 week holiday in the future.

So I put the issue to bed until after the holiday, but I'm feeling a bit guilty now. Essentially I intend to go on holidays (we leave in 7 weeks), and then come home and try to find a new job.
I already know they aren't replacing me while I'm away, the owner of our business (in another branch) was too disorganized to hire + train someone new, so our little office will go from 2 to 1 (+ 2 in warehouse) while I'm gone. I know this stresses out my manager, as he will have to cope with everything alone while I'm gone.

Should I tell him I'm unhappy with my position and will be job hunting after my holiday? My fear is I will come back to no job entirely though!

(As a side note, I haven't told my manager I'm unhappy in my position, as there's only two of us. Essentially if I don't like my duties, I simply need to ship out, there's no way to reorganize them, and I don't hold it against him. It's just unfortunate that this job isn't the best fit it could be for me.)

I'm in Australia, have no contract exempt/non-exempt status or anything like that to consider. Its more that we're such a little team I don't want him to think I'm screwing him over.

This is tricky. A lot of it depends on your relationship with your employer and your knowledge of how willing they've been to work with other people in similar situations. If you were a very long-time employee, I'd say to go ahead and give them a heads-up now ... but at 1.5 years and a long vacation planned, I'd be more cautious.

If you talk to them now, you risk them either reneging on their agreement to let you take the long trip (because they have no more incentive to keep you happy) or replacing you before you're ready for it.

Regarding the ethics of it and the guilt you're feeling: It's true that I wouldn't be thrilled if I gave an employee special permission to take eight weeks off and she quit soon after returning. But these things happen; people move on to new jobs, and employers know that (well, the sensible ones do). The fact is, they approved your vacation time, and they didn't ask you for any sort of long-term commitment in exchange. So I don't think it's crazy to look at this as two entirely separate issues.

Additionally, you don't know how long the job search will take once you return; if the Australian job market is anything like the U.S.'s right now, you may end up staying there long enough that the vacation will become a non-issue anyway.

Ultimately, I think this illustrates the need for employers to make it safer for employees to be honest with them when they're thinking about leaving. The reason most employees aren't candid about it is because they have reason to think they'll be pushed out earlier than they wanted to leave (often because they've seen that happen to others). So it's in employers' best interests to create an environment where employees know they can safely talk about this sort of thing, but too few of them do, and they end up with employees who can't safely divulge their plans.