People who have lost their employer-provided health insurance because of a layoff, early retirement, or other reasons are turning to forming a small business, or using an existing one, to buy a group policy. The strategy is used by groups as small as one person, and is particularly useful for people with chronic health problems that insurers refuse to cover or that result in steep premiums. Group health plans, under federal law, are required to cover such conditions, as long as the individual doesn't go uncovered for more than 63 days.