The paid sick leave trend is gaining traction. In his 2015 State of the Union address, President Obama called for national legislation guaranteeing paid sick leave for workers. While Congress has not yet taken any action, three local jurisdictions enacted paid sick leave laws affecting private employers in 2015 so far.

Three states, California, Connecticut, and Massachusetts, and nearly 20 cities have passed paid sick day legislation. These cities include Oakland and San Francisco, California; Bloomfield, East Orange, Irvington, Jersey City, Montclair, Newark, Passaic, Paterson, and Trenton, New Jersey; New York City; Eugene and Portland, Oregon; Philadelphia; Seattle and Tacoma, Washington; and Washington, D.C. Some of these laws, such as those in California and Massachusetts, will become effective in 2015, while others are already in effect. Understanding what is required by these laws has never been more important.

Generally, paid sick leave laws allow employees to take paid time off to diagnose, care for, or treat their own, or a family member’s, illness, injury, or health condition, or to obtain preventative medical care. Some states and cities—such as California, Connecticut, Eugene, Portland, Seattle, and Washington D.C.—allow employees who are victims of domestic violence, sexual assault, or stalking to take paid time off as well. In addition, New York City, Portland, Seattle, Tacoma, and certain cities in New Jersey allow paid leave in connection with the closure of an employee’s place of business due to a public health emergency or an employee’s need to care for a child whose school or place of care has been closed due to a public health emergency.

While some of the laws cover all employers, regardless of the number of employees, paid sick leave laws in Connecticut, Jersey City, New York City, Philadelphia, and Seattle do not apply to employers that employ less than a specified number of employees. Similarly, the laws in Jersey City, Massachusetts, New York City, and Portland provide that, even when a smaller employer is not required to provide paid sick days, those employers must still allow employees to take unpaid time off.

The threshold for employees’ eligibility to accrue sick time differs by location, but most laws require that employees (including part-time and temporary employees) work a certain number of hours in a year in order to be eligible. For example, the ordinances enacted in New Jersey require that employees work more than 80 hours in a year in order to qualify for paid sick leave, while Philadelphia requires an employee to work at least 40 hours in a year.

While the accrual of sick time generally begins immediately upon hire, most sick leave laws provide that employees become eligible to actually use sick time after their 90th or 120th day of employment. Many of these laws dictate that employees accrue one hour of sick leave for every 30 hours worked (or 40 hours worked in Connecticut and Philadelphia). However, in places such as Seattle and Washington, D.C., accrual is based on the number of employees the business employs, so that employers with fewer employees accrue hours at a slower rate than those employers that employ greater numbers of employees.

Another major difference among various sick leave laws is the incremental use of sick time. In Washington, D.C., for example, employers must allow employees to use sick time in one-hour increments. In California, employees can use sick time in two-hour increments, while in New York City, employers can require that employees use a minimum of four hours of sick time at a time.

Essentially all the paid sick time laws require employers to either provide notice to employees of their rights under the law upon hire or display a poster containing the requisite information in their business establishment. Most of the laws require employers to maintain and retain adequate records of their compliance with the laws as well. Some of the laws even go so far as to require employers to track remaining sick time on employees’ pay stubs.

The concern with the hodgepodge of sick leave laws popping up across the country is, of course, remaining in compliance, particularly for companies that operate in multiple locations. Many employers are opting to create a single sick leave policy that complies with all of the laws applicable to their various locations, while others have created separate policies for each location.

In any event, employers should keep an eye out for new sick leave laws in every jurisdiction in which they do business.