Hi,
Take a look at the following. DMAX is the way to go
Private Function AssignNextCheckNum() As Long
Dim LargestChkNum As Long
LargestChkNum = Nz(DMax("ChkNum", "CheckRegT", "AccountID=" & AccountCombo), 0)
LargestChkNum = LargestChkNum + 1
AssignNextCheckNum = LargestChkNum...