You say the employee # occurs twice on each page. The following macro will insert a page break before the first of each pair of employee #s. If the employee # isn't in the first paragraph for each payslip, a minor code adjustment can be made to accommodate that - you just have to tell us which paragraph on each page it's in. Until that adjustment is made, you'll probably also find the macro deleting the wrong first character in the document, too.
Code:
Sub Demo()
Application.ScreenUpdating = False
Dim i As Long
With ActiveDocument.Range
With .Find
.ClearFormatting
.Replacement.ClearFormatting
.Text = "<[0-9]{7}"
.Replacement.Text = ""
.Forward = True
.Wrap = wdFindStop
.Format = False
.MatchWildcards = True
.Execute
End With
Do While .Find.Found
i = (i + 1) Mod 2
If i = 1 Then
.Paragraphs.First.Range.InsertBefore Chr(12)
End If
.Collapse wdCollapseEnd
.Find.Execute
Loop
.Characters.First.Delete
End With
Application.ScreenUpdating = True
End Sub