Shortly after reports surfaced on Tuesday about Microsoft preparing for a proxy fight to convince Yahoo shareholders to agree to a takeover deal that the Web pioneer’s board has rejected, Yahoo announced a new severance plan for its employees if the company was sold.

Under the new plan , any Yahoo employee who is dismissed without good reason within two years of a change of control in the company will receive their annual base salary and certain benefits for at least four months and up to 24 months depending on position. Vesting of stock options and other equity-based compensation will be accelerated if a Yahoo employee is laid off after a sale.

Silicon Alley Insider’s Henry Blodget thinks Yahoo’s new severance plan could cost Microsoft between $1 billion to $3 billion if they seal a deal. There are a lot of assumptions baked into how he gets to this figure, but it’s an interesting figure nonetheless. If the former Wall Street analyst’s math is correct, then Microsoft’s estimated $1 billion in “synergies” it expects to wring out of Yahoo from cost cutting and revenue benefits doesn’t look so hot anymore– at least not in the first year.