In some countries, certain benefits attract lower tax if provided by the employer in-kind rather than through a cash allowance, but greater administration may be involved in delivering benefits this way. Look at your major host locations to see if the tax savings using this approach outweigh the administrative hassle and costs involved for your company.
Lump-sum and core-flex approaches may present a way to give assignees flexibility while reducing admin costs, but can bring a different set of challenges regarding duty of care, unexpected exceptions and tax compliance (which may increase the administrative burden you were trying to avoid). While these approaches have their advantages, make sure you’ve weighed up and addressed the potential challenges before going ahead with them.