Any purported variation of a contract of employment that is, or will be, transferred under the Transfer of Undertakings (Protection of Employment) Regulations 2006 (TUPE 2006), SI 2006/246, reg 4(1) is void 'if the sole or principal reason for the variation is the transfer'. However, a variation of the contract of employment of a transferring employee will not be prevented, ie the variation will not be void: • if the terms of that contract of employment permit the employer to make such a variation, or • if the sole or principal reason for the variation is an economic, technical or organisational reason (ETO reason) entailing changes in the workforce and the employer and the employee agree that variation See Practice Note: TUPE—variation of contract terms. If, at