Keiath,
So do you want the sum in the footer of the subform or on the main form?
You can do it in the footer of the subform.
Open the subform in design view.
Create a text box control in the footer.
For the Control Source of that box, enter this:
Code:
=DSum("[Amount]","NameOfSourceForSubform","[Description]=Prepayments")
Of course, you will need to provide the name of the table or query that is the source for the form. You can also Provide the Caption for the Label for this text box as something like "Sum of Prepayments:"
Then do the same for the accruals.
You can also do this on the main form, if you like, but it sounds like that is your second choice.
HTH
_________________
Regards,
Marvin M 
Windows 7 Professional, MS Access 2007/2010
Windows 8 Professional, MS Access 2013
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