Kindly guide on the following issue
1. An official of a PSU was deputed to Japan for a period of 18 months, who is treated equivalent to 'Minister'
2. He was entitled for allowance at par with that of 'Minister'
3. Japanese authority had paid him certain allowance in their currency (which is lower than the amount he was actually eligible for). The amount was received in Japan only.
4. Now, the difference amount is being paid by the PSU to him, in India( Eligible amount , less already paid by Japanese authority ).This is for the period of service at Japan.
Query
Whether the differential amount beng paid now to the official,by the PSU -in India, for the service provided at Japan is taxable or not?