Flights and Taxis would be considered travel expenses and nothing to do with subsistence. Subsistence payments are in respect of food & accomodation. If the company is paying for accomodation and meals then you can't claim subistence on top of that, it would be one or the other - either they pay you a daily subsistence rate for each day spent out of the country which covers the cost of your accomodation & meals (and you don't have to submit receipts), or they can pay you the actual amount that you incur (on the basis of submitted receipts)