Any amounts received by an employee for the assignment or release of all his rights to receive, after termination of his employment and for a period of not less than five years or for a period ending with his death, a percentage of the profits or receipts of his employer attributable to a time subsequent to such termination, are considered received from the sale or exchange of a capital asset held for more than six months if the following requirements are met:
The requirement that the assignment or release be made after the termination of the employee's employment contemplates a complete and bona fide termination of the relationship of employer and employee. This requires more than a mere termination of such relationship under the particular contract or contracts of employment pursuant to which the employee acquired his rights in the future profits or receipts of the employer. The contract need not expressly provide that the employee shall share in the future profits or receipts of the employer for a minimum period of five years. However, if the contract does not expressly so provide and the assignment or release is made before the expiration of five years following the termination of employment, the terms of the contract considered in conjunction with the facts in the particular situation must establish that the rights of the employee to a percentage of future profits or receipts, in all probability, will extend to a period of not less than five years from the date of termination of employment or for a period ending with his death. Section 1240 has application only to an assignment or release made by the employee who acquired the right to a percentage of future profits or receipts of the employer, and has no application to amounts received other than as payment for assignment or release of such right. Section 1240 has no effect upon the determination of the income tax of the employer making the payment to the employee.
26 C.F.R. §1.1240-1