Washington's Paid Sick Leave Law, enacted by Initiative No. 1433 in 2016, requires employers to provide paid sick leave to employees. 

Employees must accrue at least one hour of paid sick leave for every 40 hours worked.  Paid sick leave must be paid at the employee's normal hourly rate of compensation.  An employee is entitled to use accrued paid sick leave beginning on the ninetieth calendar day after the commencement of his or her employment.  If an employee does not use all of his or her available paid sick leave by the end of the accrual year, the employer must carry over balances of 40 hours or less to the next year.  Employers may also opt to provide more generous paid leave policies and permit use of paid sick leave for additional purposes. 

An employee may use paid sick leave for the following reasons:

• for the employee's mental or physical illness, injury, or health condition or for the employee to seek medical diagnosis, care, or treatment or other preventive medical care;
• for the employee to provide care for a family member with a mental or physical illness, injury, or health condition, or to assist with the care of a family member needing medical diagnosis, care, or treatment or other preventive medical care;
• when the employee's place of business has been closed by order of a public official for any health-related reason, or when an employee's child's school or place of care has been closed for such a reason; or
• the employee is absent for reasons qualifying the employee for leave under the Domestic Violence Leave Act. 

For the purposes of paid sick leave taken to provide care for family members, as described above, the term "family member" includes an employee's:

• child (a biological, adopted, or foster child, stepchild, or a child to whom the employee stands in loco parentis, is a legal guardian, or is a de facto parent, regardless of age or dependency status);
• parent (a biological, adoptive, de facto, or foster parent, stepparent, or legal guardian of an employee or the employee's spouse or registered domestic partner, or a person who stood in loco parentis when the employee was a minor child);
• spouse;
• registered domestic partner;
• grandparent;
• grandchild; or
• sibling.

Employer may require employees to give reasonable notices of absences.  For absences exceeding three days, an employer may require verification that an employee's use of paid sick leave is for an authorized purpose.  If an employer requires verification, verification must be provided to the employer within a reasonable time period during or after the leave.  An employer's requirements for verification may not result in an unreasonable burden or expense on the employee and may not exceed privacy or verification requirements otherwise established by law.

State law requires transportation network companies (TNCs) to provide drivers paid sick time at a comparable rate and for comparable reasons to what is required for employees.  This includes paid sick leave of one hour for every 40 hours of passenger platform time worked.  Drivers are eligible to:  (1) accrue paid sick time upon recording 90 hours of passenger platform time on the TNCs platform; (2) carry over up to 40 hours of unused paid sick time to the next year; and (3) use sick time in increments of four hours or more.

The definition of "family member" is expanded to allow for employees to use paid sick leave to provide care for additional specified persons due to a mental or physical illness, injury, or health condition, or to assist those specified persons who need medical diagnosis, care, or treatment or other preventive medical care.  The definition is expanded to include an employee's: 

• child's spouse;
• grandchild (a child of the employee's child, based on the definition of child in underlying law);
• grandparent (a parent of the employee's parent, based on the definition of parent in underlying law);
• any individual who regularly resides in the employee's home or where the relationship creates an expectation that the employee care for the person, and that individual depends on the employee for care; or
• any individual who regularly resides in the employee's home, unless the individual does not have an expectation that the employee care for the individual.

An employee may also use paid sick leave when his or her child's school or place of care has been closed due to a weather or public emergency.

Comparable changes are made to the paid sick time laws for TNC drivers, allowing those drivers to use paid sick time under the same circumstances.