Microsoft's tax avoidance by use of now familiar sales operations in places like Ireland, Puerto Rico and Singapore saves them $4.68 billion in tax a year.
The best estimate of the world aid budget that I can find is $133.5 billion a year.
So Microsoft avoids a sum in tax equivalent to 3.5% of the world aid budget each year.
Maybe Bill Gates might like to discuss the social justice in that. Many of the savings will, of course, be in countries where aid is delivered.