The RFC assessment is a function-by-function assessment based upon all of the relevant
evidence of an individual's ability to do work-related activities. At step 4 of the
sequential evaluation process, the RFC must not be expressed initially in terms of
the exertional categories of “sedentary,” “light,” “medium,” “heavy,” and “very heavy” work because the first consideration at this step is whether the individual can do
past relevant work as he/she actually performed it.
RFC may be expressed in terms of an exertional category, such as light, if it becomes
necessary to assess whether an individual is able to do his or her past relevant work
as it is generally performed in the national economy. However, without the initial
function-by-function assessment of the individual's physical and mental capacities,
it may not be possible to determine whether the individual is able to do past relevant
work as it is generally performed in the national economy because particular occupations
may not require all of the exertional and nonexertional demands necessary to do the
full range of work at a given exertional level.
At step 5 of the sequential evaluation process, RFC must be expressed in terms of,
or related to, the exertional categories when the adjudicator determines whether there
is other work the individual can do. However, in order for an individual to do a full
range of work at a given exertional level, such as sedentary, the individual must
be able to perform substantially all of the exertional and nonexertional functions
required in work at that level. Therefore, it is necessary to assess the individual
s capacity to perform each of these functions in order to decide which exertional
level is appropriate and whether the individual is capable of doing the full range
of work contemplated by the exertional level.
Initial failure to consider an individual's ability to perform the specific work-related
functions could be critical to the outcome of a case. For example:
At step 4 of the sequential evaluation process, it is especially important to determine
whether an individual who is at least “closely approaching advanced age” is able to do past relevant work because failure to address this issue at step 4
can result in an erroneous finding that the individual is disabled at step 5. It is
very important to consider first whether the individual can still do past relevant
work as he/she actually performed it because individual jobs within an occupational category as performed
for particular employers may not entail all of the requirements of the exertional
level indicated for that category in the Dictionary of Occupational Titles and its related volumes.
The opposite result may also occur at step 4 of the sequential evaluation process.
When it is found that an individual cannot do past relevant work as he or she actually
performed it, the adjudicator must consider whether the individual can do the work
as it is generally performed in the national economy. Again, however, a failure to
first make a function-by-function assessment of the individual's limitations or restrictions
could result in the adjudicator overlooking some of an individual's limitations or
restrictions. This could lead to an incorrect use of an exertional category to find
that the individual is able to do past relevant work as it is generally performed
and an erroneous finding that the individual is not disabled.
At step 5 of the sequential evaluation process, the same failures could result in
an improper application of the rules in appendix 2 to subpart P of the Regulations
No. 4 (the “Medical-Vocational Guidelines” ) and could make the difference between a finding of “disabled” and “not disabled.” Without a careful consideration of an individual's functional capacities to support
an RFC assessment based on an exertional category, the adjudicator may either overlook
limitations or restrictions that would narrow the ranges and types of work an individual
may be able to do, or find that the individual has limitations or restrictions that
he or she does not actually have.