What is the 'Ultra-Millionaire Tax Act' proposed in the US?

Several US senators have proposed 'Ultra-Millionaire Tax Act' to narrow the wealth gap by asking the wealthiest 1 lakh households to pay their fair share. It proposes a 2% annual tax on households with net worth between $50 million and $1 billion. It also proposes a 1% annual surtax (3% tax overall) on households with net worth above $1 billion.