Having great deals of cash and possessions may seem to instantly certify someone for a jumbo home mortgage, but some upscale customers still face credit-score obstacles.

In a study launched last month, 40% of respondents who make $100,000 a year or more concern that their credit rating will injure their homebuying capability in 2012, according to credit-reporting company Experian. And 29% of the affluent respondents surveyed said they were working to improve their credit ratingscredit report to certifyobtain much better terms on a homea home mortgage. The findings were based on a February survey of 500 individuals who just recently bought a home or were planning to purchase a home within a year.