Giving same-sex couples marriage rights will be good for the economy, according to a new study.

The research entitled Effect of Marriage Equality and Domestic Partnership On Business and the Economy from the University of California, Los Angeles documents gains to businesses from happier and healthier workers that would outweigh new costs for benefits.

It comes after Washington, New York and California have all recently rejected allowing gay marriage.

Co-author of the study, Dr M. V. Lee Badgett, said equal treatment of couples in the world of business creates a more productive workplace, she said: “Policymakers and businesspeople have not fully recognised the enormous potential gains to the economy from treating same-sex couples equally.

“Our study shows that equal treatment of couples in the business world attracts heterosexual employees and creates more productive workplaces for gay, lesbian, and bisexual employees.”

The study documents numerous research findings on different aspects of the economy. Gay, lesbian, and bisexual (GLB) employees who get domestic partner benefits are more open in the workplace and have better mental health outcomes than employees that do not get such benefits.

It found that partner benefits increase job satisfaction and job retention, reducing recruitment and training costs for companies. Although businesses will have some one-time administrative costs, ongoing added costs to employee benefit plans will be low, since few employees will have new spouses or partners to cover.

The economy gains in other direct ways, as well, according to the report,”spending on new weddings alone would generate $2 billion for businesses in the wedding industry,” reported co-author Gary Gates, senior research associate at the Williams Institute.

“Places that allow same-sex couples to marry have reported noticeable boosts in business for hotels, caterers, florists, and other wedding-related businesses. Our study reports the expected wedding impact for each state.”

The study notes that differences across states in policies toward same-sex couples can be confusing and costly for businesses.

Complexity and uncertainty make it difficult for employers to know how to treat employees and their partners across jurisdictions.

Employers also risk losing employees to jobs in states with more favourable policies.