Can an employer require me to work full-time even though I only agreed to part-time and have been working part-time since my employment began?
In most cases, yes.
Recently, a potential client had this issue. She was working four days a week but her employer wanted her to work five days per week. Legally, the employer can require her to do so.
In any situation in which the employer asks the employee to go from part-time to full-time, the employee is absolutely free to decline. Doing so, however, may jeopardize her employment. The employer would be within their rights to say, "We need someone full-time; unless you can do that, we have to let you go." If the employee refuses, the employer may decide to terminate the employee and there would be no repercussions to the employer for doing so.
Here are scenarios in which requiring a part-time employee to work full-time may be illegal:
-The most obvious and likely scenario is if the employee is working part-time as an accommodation for her disability and the employer KNEW of the disability. In this woman's case, she had no known disability and her employer knew that. The employer needed her to work more hours and they were within their rights to ask her.
On the other hand, if she had a disability, the employer technically could not let her go. Employers are required to provide reasonable accommodations to disabled employees. That includes actively restructuring their business to provide the accommodations. The only time the employer is not required to take such actions is if accommodating a disabled employee posed an undue hardship. For example, an employee whose job required 95% lifting suddenly cannot lift and there is no other available job for the employee to do, the employer is under no obligation to create a job for the disabled employee just to accommodate him or her. The employer may be under the obligation to consider other options, like leave, that might allow the employee to return to her job, depending on the circumstances.
Another scenario where requiring a part-time employee to work full-time may be illegal: If the employer requires full-time because ultimately they want to terminate the part-time employee's employment based on an illegal reason--i.e., for retaliatory or discriminatory purposes. Here are some examples:
-Employee works part-time because she has a second job that is under contract and thus she cannot easily quit that second job (not a protected activity). Employer knows that employee has a second job that is under a contract. Add these facts: employee is over 40, is the only member of the team who is over 40, employee is one of five part-time employees roughly ranked the same, and the employer is only requiring her to work full-time, it could be fair to say that there may be some wrongdoing by the employer in requiring only her to work full-time. In other words, what would need to be proven is that the ultimate goal of the employer in suddenly requiring this employee to work full-time was to force the employee to quit or use the "refusal" as a basis to terminate her based on her age.
-Employee works part-time because she has a two-hour commute, one way, and doing that commute more than four days per week would be too much, a fact that has been conveyed to the employer (not a protected activity). Add these facts: employee's manager has made racist comments to or about the employee and employee complains to HR. If, suddenly, that employee is required to work full-time, there may be some wrongdoing by the employer in requiring her to work full-time. Again, what would need to be proven is that the purpose of requiring full-time was for the employee to quit or use the refusal as a basis to terminate her based on her race or in retaliation for complaints.
Bottom line: unless the request is based on an illegal reason, your employer is within their rights to ask you to change your work schedule from part-time to full-time and refusing to do so could result in your termination.