RetireJapan

So it's looking like I've got a good chance of getting a new job soon. I have max vacation days saved up, which means I will be able to take 6 weeks of vacation to finish out the old job. The company wants 3 months notice, meaning I will work 6 weeks, and then use up my saved vacation the last 6 weeks (as another person did a while back). For example, if I inform the company of my intention to quit July 1st, I would start vacation August 15th, and my employment would terminate Sept 30th.

Does anyone foresee any issues starting the new job, during the 6 weeks vacation (working August 15th to Sept 30th in the example)? I would essentially be enrolled full time at two companies earning two full time salaries, by A) working 40 hours a week and receiving salary and B) receiving salary through 5 paid vacation days per week. I'm not trying to hide anything from anyone, and I'll alert the new company to what I'll be doing. I expect to pay higher taxes for the overlapping time, which is fine, but I have no idea how Pension and Shakai Hoken will work. Oh, I'm a permanent resident, FYI, so there are no VISA issues relating to different types of work.

Ravlen

If I'm not mistaken you can't be employed full-time at both companies.

They'll want proof you're done at your previous company and I believe will not be able to employ you legally until that takes place.

Another thing to consider is that a 3month notice is extremely onerous and not legally enforceable. I think the legally enforceable notice is 2 weeks though requiring one month is common in most companies and most people are a good sport about it. Of course, you don't want to burn bridges, so being reasonable may be better for your reputation, and it's only reasonable to help get your replacement up and running, but there is absolutely no way they can enforce the 3 month requirement, and quite frankly it strikes me as onerous. 3 months is a long time...

You might be able to get them to cash out your vacation days, but I'm not sure about whether that's possible or not

I confirm what jcc said:
Legally it's only 2 weeks notice, and a lot of people did that in my team because it's the law.

My company also asks the employees if they prefer to have the holidays paid (so that they stay longer for passing the tasks to other people), rather than using them before leaving.
Basically here people tends to say 2 weeks before "hey I leave and I take my holidays so tomorrow I'm not here anymore" ahah...

Feel free to do what you want the most if you want to stay in good relationship with your current employer, but they have no right to ask you 3 months so if I was you I'll just take my holidays a little before to use them all and start fresh in a new company.

Somehow this is relevant to me now.
I am about to join a new company.
The notice period in my previous company says 6 weeks, but I gave my notice 4 weeks prior to my requested end date.
When they asked about it, I just politely requested that date and mentioned a bit about Japan labor law requiring only two weeks.
Eventually, the manager approved it

Not sure if this will work for you, but let's hope for the best!

Is it illegal to be employed "full time" at two different jobs, or just hard to find a company that will hire you until you are full out of the last company? I'm sure I could get my manager to write a letter proving that my employment is ending soon and that I'm just "employed" until my vacation days run out (and that I won't be in the office anymore)... But if it's illegal I won't try (of course).

Ravlen