Initially you may find it possible to send employees abroad on an ad hoc basis, but as volume increases problems can arise.  

You may start to find that costs escalate and become difficult to track; it becomes more difficult to maintain the employee's home salary (what will you pay them on return); consistency becomes an issue as employees compare packages, and tax (on benefits as well as salary) can become a very serious issue.

ECA's Consultancy has written (and reviewed) policies for hundreds of companies, from smaller companies sending employees abroad for the first time to huge multinationals with thousands of expatriates. 

Our unique position in the international HR community gives us the required experience and knowledge of best practice to advise on policy across different industries and find the best solution for your company.