This is a taxable benefit, which aims to offer income for terminated employees. SUB is mostly comes when when terminated employment has been due to injury, training or illness. There are various types of supplemental unemployment benefits, of which the main ones are the furlough and extended layoff benefits. 

The furlough benefit, is usually provided when employees hours are reduced; which means that employees work less hours due to the reduction of the workforce within the organization. Under this setting, payments which are not wages are included in the SUB. With the extended layoffs, employees employees get laid off temporarily for cost cutting purposes. 

Most organizations with expected periods of downtime (specifically in the construction sector), usually have SUB plans in place in order to help their employees to maintain an income while they are out of work. 

Applying for a SUB

In order to receive SUB pay, former employees must be eligible state unemployment benefits and be willing to participate in their employer's SUB plan. Employees are also required to file a claim with the unemployment insurance office in the state where they worked.