Zenefits, a fast-growing startup with cloud software for managing health insurance and other employee benefits, is announcing today the new ACA Compliance Automation feature to ensure that companies provide health care in accordance with the rules of the U.S. Affordable Care Act.

Zenefits provides its core software free of charge — the startup brings in revenue by charging when companies sign up employees for health care coverage — and the new feature is free, too, according to a statement.

The tool, which is intended for small businesses, will automatically submit forms to the federal Internal Revenue Service on the part of companies. It also figures out which employees count as full-timers — and that exact number matters, because regulations vary depending on company size.

Other companies ensure compliance with the ACA, but not for free, Zenefits says. Competitors include Justworks Paychex, TriNet, and Gusto (formerly ZenPayroll).

San Francisco-based Zenefits, which started in 2013, announced a $500 million funding round at a $4.5 billion valuation earlier this year.