Also read: factoids, LGBT, transgender, domestic-partner benefits

For the eighth year in a row, companies on The DiversityInc Top 50 Companies for Diversity^® list and DiversityInc's 25 Noteworthy Companies list are among the companies earning a perfect score on the Human Rights Campaign's Corporate Equality Index survey, a national rating that grades Fortune 500 companies and national law firms on their LGBT efforts.

This year, 39 of The 2009 DiversityInc Top 50 Companies for Diversity (78 percent) achieved a 100 percent rating on the HRC's 2010 CEI. This is up from 8 percent in 2001, when the first CEI list was published.

The CEI is an in-depth look at company policies and employee benefits. This year, more than 1,500 companies were invited to participate in the 2010 CEI, of which 560 were scored.

In order for companies to earn a perfect score of 100, they must have a nondiscrimination policy that includes protection for transgender employees. Companies must also offer domestic-partner health benefits as well as house an LGBT employee-resource group or a diversity council and engage in appropriate and respectful advertising and marketing.

DiversityInc incorporates this criterion when determining The DiversityInc Top 10 Companies for LGBT Employees list. No company can be on this list that doesn't receive a 100 percent CEI rating. In addition, in order to be considered a DiversityInc Top 50 company, applicants must offer benefits to same-sex partners of employees.

In March, the HRC updated its criteria for companies to achieve a 100 percent rating on its CEI. The change reflects the need for a growing acceptance for those who are transgender. Under the new criteria, employers will have to grant employees access to "at least one insurance plan that contains no exclusions for transgender-specific care and recognizes internationally accepted medical standards of care."

Previously, the HRC required insurance plans to cover "one out of five categories of treatment that were designed to educate employers and their insurance carriers about the insurance needs of transgender people."

"These new criteria get right to the core issues of how insurance plans exclude transgender employees," Meghan Stabler, national transgender activist and HRC business council member, said in a written statement. "By aligning the new requirements to 'medically necessary' coverage defined by recognized standards of care and removing transgender-related exclusions from healthcare plans, we have significantly raised the bar allowing businesses to enhance their commitment to all employees. Right now, hundreds of businesses will begin working to expand coverage to transgender employees. With this powerful new tool, our community must set out to educate human resource and benefits professionals about why these benefits are needed, not just for individual employees and their dependents, but to secure employer-of-choice status in the LGBT community."

Other requirements to achieve a 100 percent HRC CEI rating include companies offering health-insurance access to same-sex partners and spouses, competency training and accountability on LGBT issues, and external engagement in the LGBT community.

In addition to offering same-sex-partner insurance benefits, in order to get the 100 percent HRC rating, companies must also offer the same fringe benefits required by law for heterosexual couples, including medical and dependent coverage, COBRA-equivalent benefits, retirement benefits, FMLA-equivalent leave and bereavement leave.