Here's the short answer: most employee benefits are not federally required, but a few come close. There is no federal law forcing employers to offer a 401(k) or to match contributions, and no law requiring an HSA contribution. Health insurance is only effectively mandated for larger employers under the Affordable Care Act, and workers' compensation insurance is required in nearly every state but governed by state law, not federal law. The details vary a great deal depending on your size and your state, so let's walk through each benefit carefully.
Health Insurance: Required Only for Larger Employers
The United States has no general rule that every employer must offer health insurance. Instead, the requirement comes from the Affordable Care Act (ACA) and its "employer shared responsibility" provision, enforced by the IRS.
Under the ACA, an "applicable large employer" (generally one with 50 or more full-time and full-time-equivalent employees) must offer affordable health coverage that meets minimum value to its full-time employees, or it may owe a tax penalty if a full-time employee receives a premium tax credit on the marketplace. Employers below that threshold have no obligation to offer health insurance at all.
So do employers have to contribute to health insurance premiums? Federal law does not set a specific contribution percentage. However, for coverage to be "affordable" under the ACA (and thus shield a large employer from penalties), the employee's share of the premium for self-only coverage cannot exceed a set percentage of household income. That percentage is adjusted annually by the IRS, so practically, large employers usually pay a substantial portion of the premium to stay compliant. Many states and insurance carriers also impose their own minimum employer-contribution rules for group plans, which is one more place where this varies by state and by insurer.
A few related federal rules matter even when coverage is voluntary. COBRA generally lets employees of employers with 20 or more workers keep group coverage temporarily after leaving, though the former employee typically pays the full premium. The ADA and Title VII require that whatever benefits you do offer be administered without discrimination, and HIPAA protects the privacy of health information.
401(k) and Retirement Plans: Voluntary at the Federal Level
No federal law requires a private employer to offer a 401(k) or any retirement plan, and none requires an employer to match contributions. A 401(k) is a voluntary benefit. When an employer chooses to offer one, the plan is governed by the Employee Retirement Income Security Act (ERISA), enforced by the U.S. Department of Labor's Employee Benefits Security Administration and the IRS.
If you do offer a plan, ERISA imposes real duties. As a plan fiduciary you must act prudently and in the interest of participants, follow the written plan terms, keep fees reasonable, and deposit employee salary-deferral contributions into the plan as soon as they can reasonably be segregated from company assets (the DOL treats undeposited deferrals very seriously, since they are employee money). You must also provide required disclosures such as the Summary Plan Description and annual fee notices.
Matching is entirely optional, but if you promise a match in the plan document, you must honor it. Some plan designs, like a SIMPLE IRA or a "safe harbor" 401(k), do require employer contributions as a condition of that specific plan type, but that is a choice you made by selecting that design, not a free-standing legal mandate to contribute.
State Auto-IRA Programs Like CalSavers
This is where many employers get tripped up. A growing number of states have created state-facilitated retirement savings programs that require employers who do not already offer a qualified plan to participate. California's program is CalSavers; other states have their own versions (for example, OregonSaves and Illinois Secure Choice).
Do employers have to contribute to CalSavers? No. CalSavers and similar auto-IRA programs are funded entirely by employee payroll deductions. The employer's role is administrative: register by the applicable deadline, add eligible employees, and remit the amounts withheld from employees' paychecks. Employers are prohibited from contributing to these accounts and from providing investment advice. The required action is enrollment and payroll facilitation, not funding.
Whether you are covered, the size threshold, and the registration deadline all depend on your state, so this varies by state. If your state has such a program, check the official program website for your registration deadline; missing it can lead to per-employee penalties. Employers that already sponsor a qualified plan (like a 401(k)) generally just need to certify their exemption.
Workers' Compensation: Required by State Law in Nearly Every State
Workers' compensation is the benefit most likely to be legally mandatory for you. It is not a federal program for most private employers; it is governed by each state's workers' compensation act and administered by a state agency (often called the Workers' Compensation Board, Division, or Commission). Nearly every state requires employers to carry workers' compensation insurance once they have employees, though the trigger (sometimes one employee, sometimes a handful) and the rules differ.
Texas is the notable outlier where private workers' comp coverage is largely optional, and several states exempt very small employers or certain categories like some agricultural or domestic workers. Because the threshold, covered workers, and benefit levels are all set by the state, this varies by state and you should confirm with your state agency rather than assume.
Workers' comp generally covers medical treatment and partial wage replacement for job-related injuries and illnesses, in exchange for the employee giving up the right to sue the employer in most cases. You can usually satisfy the requirement by buying a policy from a private insurer, a state fund, or by qualifying as a self-insured employer.
The Uninsured-Employer Hook
Failing to carry required workers' comp coverage is one of the more dangerous compliance gaps in employment law. Consequences commonly include: