Using form control checkboxes to clear ranges on other pages- VBA Excel

[p45cal]

try changing:
If CheckBox.Value = False Then
to:
If CheckBox.Value = xlOff Then

You could also reduce your looping a bit:

Sub CommandButton1_Click()
Dim ws As Worksheet, CheckBox, c

For Each CheckBox In CheckBoxes
  If CheckBox = xlOff Then
    Set ws = Nothing
    On Error Resume Next
    Set ws = Sheets(CheckBox.Caption)
    On Error GoTo 0
    If Not ws Is Nothing Then
      For c = 1 To ws.Cells(Rows.Count, 8).End(xlUp).Offset(1, 0).Row    'if not checked, looks on current worksheet (within loop) and if any "Y" or "y" vals, clears them
        If Application.Trim(UCase(ws.Range("H" & c).Value)) = "Y" Then ws.Range("H" & c).ClearContents 'caters for upper and lower case and leading/trailing spaces.
      Next
    End If
  End If
Next CheckBox
End Sub