Washington’s health care revolving door is spinning fast as the new online health insurance marketplaces, a central provision of President Obama’s health care law, are set to open Oct. 1. Those who had a hand in the law’s passage are now finding lucrative work in the private sector, as businesses try to understand the complex measure, reshape it by pressing for regulatory changes — or profit from it.

That means boom times for what might be called an Obamacare cottage industry, providing work for dozens of former administration and mostly Democratic Congressional officials whose immersion in health policy minutiae, and friendships, make them invaluable to private business.

Dr. Dora Hughes, for example, has a medical degree from Vanderbilt and a master’s in public health from Harvard and never envisioned joining a law firm. But Dr. Hughes, a former Obama administration official, has something Washington lawyers and lobbying shops covet: an insider’s understanding of the new health care law.

After nearly four years as counselor to Health and Human Services Secretary Kathleen Sebelius, she left government last year to work for Sidley Austin, which represents insurers, pharmaceutical companies, device makers and others affected by the law. She is not a registered lobbyist, but rather a “strategic adviser,” although some call that a distinction without a difference.