When is a Leave of Absence an Appropriate ADA Accommodation? As part of the law, you may have to let employees take some time off. Here are three questions to ask when making your decision.

The Americans with Disabilities Act (ADA) requires employers to provide an employee who has a physical or mental disability, or a record of such a disability, with a workplace modification or adjustment -- an accommodation -- that will enable the employee to perform the essential functions of his or her position.

Most employers today are familiar with the interactive process they must engage in when an employee requests an accommodation due to a disability. In recent years, it has become clear that employers must consider a leave of absence as a reasonable accommodation even when the employee has exhausted or does not qualify for other leaves of absence.

Leave can allow the employee to obtain medical treatment, therapy, or rehabilitation; obtain or train on assistive equipment or a service animal; or simply recuperate from an injury or illness. Leave as an accommodation only has to plausibly enable the employee to perform his or her job upon return -- certainty is not required.

Related: Hiring Employees With Disabilities

If an employee's disability and the need for leave as an accommodation are not obvious, the employer can obtain medical information to help understand how a leave will enable the employee to continue performing his or her job.

An employer can also deny a leave request and offer an effective alternative accommodation that would allow the employee to remain on the job and eliminate the need for leave. However, if the employee's leave request also qualifies under the federal Family and Medical leave Act, then the employee has a right to take a leave of absence of up to 12 workweeks in a 12-month period, even if another accommodation would enable the employee to continue working.

Yes, it's complicated. Yes, employers often get it wrong.

So when is leave an appropriate accommodation? Here are three questions to ask:

1. Is the leave of absence a reasonable accommodation? Details such as the length of a continuous leave, the unpredictability and frequency of intermittent absences, the degree or lack of certainty of the employee's return to work date, etc., require a case-by-case analysis.

Although an employer may have to modify time and attendance policies as a reasonable accommodation, the following are generally not reasonable leave accommodations: an indefinite leave, complete exemption from time and attendance requirements, or irregular, unreliable attendance.

Related: 4 Factors in Crafting Your Company's Leave Policy

2. Will the leave be an effective accommodation? Whether leave is effective as an accommodation is a fact-specific inquiry weighing many factors, such as:

• Nature of the employee's disability and limitations
• The essential and marginal functions of the employee's position
• What purpose the leave will serve to enable the employee to perform the essential functions

3. Will the leave impose an undue hardship on the employer's business? If a requested leave of absence is reasonable and effective, the employer's only ground for denying the leave as an accommodation is that it will impose an undue hardship. Undue hardship is a "significant difficulty or expense" in relation to the size of the employer, the resources available and the nature of the operation. A moderate inconvenience or expense is not an undue hardship. There are no set rules on how long of a leave constitutes an undue hardship. The employer must support its claim of undue hardship with specific facts and evidence.

An employer does not have to grant an endless number of leave extensions. However, once a leave request has been granted and survived by the employer and its workforce, it becomes problematic for the employer to argue that an extension of a few more days or weeks turns the leave into an undue hardship.

Employers should request updated medical information to support each extension request and have the medical provider explain the basis for the opinion that this extra time will indeed, this time, enable the employee to return to work. After more than one extension request, it may be that the leave has become "indefinite" with no prediction of a return to work date -- in other words, an unreasonable accommodation.

Related: What Should I Know About Terminating An Employee Due To Medical Problems?