When a sole trading source is set up for Self Assessment, the
computer allocates a unique identifier to that source. This is not
known by the taxpayer and is not on the return. The unique
identifier known as the source reference is shown in function
MAINTAIN SOURCES.
Where a taxpayer includes more than one trading source in
their SA return, the source reference must be entered for each
source during capture. This will allow the Compliance Officer to
distinguish the sources during Check Later.
