Potential IRS changes to the tax-free treatment of spin-offs should not affect previously filed requests, the web portal said yesterday, adding that Yahoo had already lodged its plan and was still working towards undertaking the transaction in the fourth quarter. The stock fell 7.6 percent on Tuesday on concerns that Internal Revenue Service changes would affect efforts to exit from Alibaba. The shares recovered somewhat yesterday. Any obstacle to the spin-off would erode the appeal for shareholders who bought Yahoo betting they essentially would get a tax-free payout when the deal closes.