double check an update query

I have a question about this update query before I run it:

UPDATE 2007_SUBMISSIONS INNER JOIN 2007_SUBMISSION_HISTORY ON
[2007_SUBMISSIONS].MEMBID = [2007_SUBMISSION_HISTORY].MembID SET
[2007_SUBMISSION_HISTORY].AMT_PAID = Round([2007_SUBMISSIONS].AMT_PAID,
2), [2007_SUBMISSION_HISTORY].SUB_TYPE = "update",
[2007_SUBMISSION_HISTORY].SUB_DATE = Date(),
[2007_SUBMISSION_HISTORY].AMT_SUBMITTED =
Round([2007_SUBMISSIONS].AMT_PAID-[2007_SUBMISSION_HISTORY].AMT_PAID,
2)
WHERE ((([2007_SUBMISSIONS].MEMBID) Not In (SELECT [MEMBID] FROM
[2007_I_04e_UPDATE_SUBMISSION_MEMBERS_Filter])));

What I think this query does is if a member is in the submission
history table and also not in the filter (assumption it is in
submission table) then
it changes the amt_paid in the submissions history table = amt_paid in
submissions - amt_paid in submissions history and it adds the
submission date of today and it rounds it before it subtracts.

Is that right?

thanks,