So. . . For Example

Starting Balance = $500
Month 1 = $600
Month 2 = $700
Month 3 = $800
And so on. . .

I'm assuming you have a field for Starting Balance and a separate Field for total Amount Accrued? If so, how about a button with an onclick event which resets the total amount?

Private Sub ResetButton_Click()

    [TotalField] = [StartingBalanceField]

End Sub

You could also build an Update Query and have it run whenever the database starts up.
Also covered in Access Expert 13.

Thanks for the quick response guys.

Dan to answer your question I do have a Start Balance Currency field in my EmployeeT.

I then created a separate table (MedicalBenefitT) to track the employee's Reimbursement Request and Date Paid. The table has the following fields: TransID, EmployeeID, RequestDate, RequestAmount, RequestType, PaymentDate, AmountPaid, and a IsPaid (Yes/No).

I then created a query (MedicalPaymentQ) using both the EmployeeT & MedicalBenefitT tables as a source for my MedicalBenefitsF (Main form) and the MedicalSheet (Subform) to enter Employee Reimbursement transactions.

I added 2 calculated fields in the footer of my subform: The first is my Total Reimburse with the following Control Source: =Sum([AmountPaid]) and the second calculates the Balance Remaining of the Benefit.

So for example... An employee's has a Starting Balance is $2000. Everytime the employee submits a request for reimburse a transaction is added to the system and whatever amount was paid to the employee, that amount automatically decreases the Starting Balance.  The system is working fine; however, the Administrator now wants to know if the database to automatically reset whatever the remaining balance is in the calculated field to $0.00 on the Anniversary Date every year, since this benefit does not roll-over. I hope this help clear things up. Again thank you all for your input.