The latest debate over the Biden-Harris administration’s economic proposals reached a boiling point on CNBC’s Squawk Box when hosts Rebecca Quick and Joe Kernen clashed with Bharat Ramamurti, an informal economic adviser to Vice President Kamala Harris’s campaign, over a controversial tax on unrealized capital gains.

The proposed tax, which would impose a 25% levy on individuals with over $100 million in wealth, has sparked intense discussion, with critics arguing it’s both unfair and potentially unconstitutional.

The tension in the discussion became evident as Quick and Kernen challenged Ramamurti on the fairness and practicality of taxing unrealized capital gains—profits that exist on paper but haven’t yet been realized through the sale of assets like stocks. Quick pointed out the fundamental issue: the tax would essentially be “pulling forward” taxes that would traditionally only be paid when someone actually sells the asset.

In defense of the proposal, Ramamurti made an analogy to property taxes, suggesting that most people are already accustomed to paying taxes on unrealized gains through property taxes. He argued that when a home’s value increases, homeowners pay higher taxes even if they don’t sell their property, implying a similarity to the proposed tax on unrealized gains.

However, the hosts were quick to push back on this comparison. Quick and Kernen noted that property taxes are fundamentally different because they are a “use tax”—taxes that directly fund local services like schools and emergency services. They also emphasized that property values don’t fluctuate with the same volatility as stocks, making the analogy less applicable.

Quick’s rebuttal highlighted the difference in purpose between property taxes and the proposed tax on unrealized capital gains. “Your value of your home never moves the way a stock moves, the way something else moves that you don’t sell,” Quick argued, underscoring the potential for significant financial burden on individuals during periods of market volatility.

Ramamurti, however, maintained that the revenue generated from this tax would create more opportunities for Americans, framing the proposal as a means to level the economic playing field.

Kernen, not convinced, raised the constitutional concerns surrounding the proposal, quipping that it might not even come to fruition in Quick’s lifetime due to legal challenges. The constitutionality of such a tax has been a point of contention, with critics arguing that taxing wealth that hasn’t been realized through a transaction could violate the Constitution’s provisions regarding taxation.

According to analysis from the Peter G. Peterson Foundation, the unrealized gains tax, coupled with an increase in the capital gains tax, could generate nearly $800 billion in new revenue for the government. But as this heated exchange on Squawk Box illustrates, the path to implementing such a tax is fraught with legal, economic, and political challenges.