Form 8838 is used to extend the statute of limitations for U.S. persons who transfer stock or securities to a foreign corporation. The form is filed when the transferor makes a gain recognition agreement. This agreement allows the transferor to defer the payment of tax on the transfer. The IRS uses Form 8838 so that it may assess tax against the transferor after the expiration of the original statute of limitations.
The latest form for Consent To Extend the Time To Assess Tax Under Section 367—Gain Recognition Agreement expires 2023-12-31 and can be found here.