1 If X is a topological (or metric) space and M is a metric space, then the set of all bounded continuous functions from X to M forms a metric space if we define the metric as above: d (f, g) = sup x in X d (f (x), g (x)) for any bounded continuous functions f and g.
Invisalign is orthodontic appliance, so since orthodontic treatment is allowed as an FSA expense, Invisalign is covered. Different companies have different rules concerning amounts set aside and the timing of how funds are used for orthodontics.
An individual who is covered by a general-purpose health FSA is not eligible to contribute to an HSA. This holds true even if the individual is covered by a health FSA sponsored by a spouse's employer. However, an individual may contribute to both an HSA and a limited-purpose FSA that's restricted to dental and vision-care expenses. Limited-purpose FSAs Limited-purpose FSA funds can only be used to pay for qualifying dental and vision expenses incurred by employees or their covered spouses and qualified tax dependents. The contribution caps for a limited-purpose FSA are the same as for a health FSA. If employees are eligible for a health FSA, there's no reason for them to have a limited-purpose FSA, since the health FSA covers the services of a limited-purpose FSA (dental and vision). Modifying Plan Documents