Working abroad can be a powerful enticement for employees, promising many benefits. But first it might be wise to see how much things costs in the newly assigned city. And considering how tight the job market is, as well as how difficult it can be to find the right talent, the ability for multinational companies to be able to post employees where they're most needed could become even more of a challenge. Read: 4 tips for moving employees abroad In Mercer's 24th annual Cost of Living Survey, such factors as instability of housing markets, low inflation and fluctuating prices for goods and services are evaluated to see how they'll affect the cost of expatriate packages for international assignees. And while it's clear that jobs in some places could raise the price to put the right employee in the right slot, these days it's not an option to discount the importance of such an action. Read: 12 top international places to retire It will cost employers more—sometimes a lot more—to place employees in some Asian, European and African cities, with Asia leading the way; four out of five of the most costly cities in the world for expatriates, it says, are in Asia. According to Mercer, its "multinational approach to cost of living develops cost-of-living indices and differentials based on a blended international spending pattern." Mercer weights goods and services the same for all location based on assuming "a convergence of spending patterns among expatriates from different nationalities," and compares "prices of similar brands and from similar retail outlets in both the home city and host city" to arrive at each city's standing. Read: Trends affecting the international health insurance industry The study uses data on housing, transportation, food, clothing, household goods and entertainment to determine which cities are more or less costly for expatriate employees. The seven cities in the slideshow are the most expensive places to send an assignee. Items listed represent purchases at medium-priced establishments, says Mercer. BenefitsPRO related reading: 10 most expensive housing markets 7 best states for retirement in the east 5 ways to keep benefits costs down