Japan tax question, airfare?

I go to Japan every year for a month for work. I am paid a salary and a per diem. All airfare & travel is covered by my employer. The salary and per diem totals much less than $10,000. If you add all the air & train fares it comes to more than $10,000. He is telling me that if he pays me more than $10,000 I will have to pay 20% in taxes to Japan. If he pays me my usual salary, and he includes the travel fares as income, the total is over this magic number of $10,000, and will cause me to have to pay this tax, making my net much less.

I find it very odd that he is including thousands of dollars of travel fares as income. This is not money I ever see, it is paid for the flight to Japan, etc.

Needless to say, I don't quite trust his understanding of the Japanese tax laws. Why would airfare be considered income? Where can I get this question answered in a definitive way.

please ask the nearest Japanese consulate or embassy. Your trip could be "a taxable benefit". for example my health care is paid by my employer and I have to report some of it.

I'm not sure but I dont think it would be the ticket for the plane ride to and from japan would be bought outside of japan meaning it can't be counted as income also your dont live in japan you only are there for work which is not so much working in japan but a trip because of work which again unless its a japanese company your pay is already taxed in your home country. Again I may be wrong but I don't think anything even remotely dealing with your pay is taxable since your visting japan for work related stuff but not officaly working in japan like if a japanese person goes to the US for a month because the company sends him there for work I dont belive he is taxed in the US. Now as for teh $10000 number he gives I think I have heard something about 10k before if your in the US it maybe the ammount of money your taking with you physicly on you out of teh country that has to be reported again I may not veen be close on any of this but it does sound strange. So in endning my massive sentance lol ask the japanese embassy asking about your type of work while in japan you may not have to worry about anything I think.

Is your boss telling you it will be taxed by your country and Japan? If it is USA, I don't think you will be double taxed.

All you need to worry about essentially is whether you're happy with your salary. It is for the company to worry about your air fares and der diem payments (you say this is all covered by the company) as this is separate and a cost for your boss to worry about. If they are covered by the company - then this will be money he pays out ON TOP of your wages. If you are getting paid less than you should be and getting excuses from your boss about these extra costs being deducted or whatever, then I think you need to look at your contract of employment.