In the RecordsetClone of your form, examine the Type and Attributes of the
Field that your controls are bound to.
As you loop through the controls on your form, the first step is to skip
over the controls that have no Control Source property (such as lines,
labels, command buttons.) For those that have a ControlSource, you can skip
the ones that are unbound (Control Source is a zero-length string), or are
bound to an expression (starts with "=".) That leaves you with those bound
to a field.
You can find the details of that field by examining:
Me.RecordsetClone.Fields(Me.Text0.ControlSource)
It is an AutoNumber of its Type is dbLong, and its (Attributes And
dbAutoIncrField) is non-zero.
This link illustrates how to go about it:
Assign default values from the last record
at:
http://allenbrowne.com/ser-24.html
The code in that link eliminates the autonumbers (so as not to try to assign
a value to them), but the process of identifying them is the same.