Microsoft CEO Steve Ballmer has pledged money to a campaign to defeat a proposed wealth tax in the software giant's home state of Washington - putting him on a direct collision course with his former boss's dad, Bill Gates II.
Ballmer has donated $100,000 to a campaign aimed at defeating Initiative 1098, a proposed income tax on state residents who earn more than $200,000.
The proposal is due to be voted on by the state legislature in November.
One of the chief architects of the tax is retired lawyer and philanthropist Bill Gates II, the father of Microsoft founder and Ballmer's former boss, Bill Gates 3.0.
According to Gates Snr's 'yes' campaign, Initiative 1098 will redistribute wealth by reducing taxes for the state's smallest businesses, and generate income for health services and public education by increasing tax on high earners, boosting funding by as much as $1 billion a year.
Philanthropy seems to run in the family. Gates the younger retired from the day-to-day running of Microsoft in 2008 to salve his own conscience by giving away his lucre via the Bill & Melinda Gates Foundation - much to the chagrin, we imagine, of his kids.
The Defeat 1098 campaign, to which Ballmer has pledged his cash, claims the measure would see the biggest hike in taxes the state has ever seen, making it difficult to lure talent to Microsoft's Redmond campus. Also among the merry men out to squash the Robin Hood proposal is multi-billionaire Jeff Bezos, the founder of internet bookseller Amazon.com.
Ballmer's donation brings funding for the two sides of the debate almost neck-and-neck, with funding for Defeat 1098 now standing at $3.4 million, against the 'yes' campaign's $3.5 million.