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I'm writing an app which is kind of a small payroll system that calculates NI but not tax. I've just got round to calculating the NI from equations that have been given to me by the tax office. The problem is my result is always 5p less than it should be. Can anybody see why??
curPercent = 10
curUEL = 27820
curEmpThreshold = 3952
Code:
Dim rsNI As ADODB.Recordset
Dim curGrossPay As Currency
Dim curEmpThreshold As Currency
Dim curUEL As Currency
Dim curPercent As Currency
Dim curCalc1 As Currency
Dim curCalc2 As Currency
Dim curResult As Currency
' Get NI Data from DB
Set rsNI = New ADODB.Recordset
rsNI.CursorType = adOpenForwardOnly
rsNI.Open "National_Insurance", conCrowd, , , adCmdTable
If not rsNI.EOF Then
curGrossPay = CCur(txtGross.Text)
curEmpThreshold = CCur(rsNI!NEL_Annual)
curUEL = CCur(rsNI!UEL_Annual)
curPercent = CCur(rsNI!Employee_Rate)
End If
rsNI.Close
Set rsNI = Nothing
' Calculate Employee Contribution
curCalc1 = curEmpThreshold / 52
' As pay period is 1, round down to whole pounds
curCalc1 = Fix(curCalc1)
curCalc1 = curGrossPay - curCalc1
If curCalc1 <= 0 Then
' No NI Contribution
Exit Sub
End If
curCalc2 = curUEL / 52
' Round up to whole pounds
curCalc2 = Format(curCalc2, "######.##")
If InStr(CStr(curCalc2), ".") <> 0 Then
' Not a whole pound, Round up
curCalc2 = Fix(curCalc2)
curCalc2 = curCalc2 + 1
End If
curCalc2 = curGrossPay - curCalc2
' If negative treat as zero
If curCalc2 < 0 Then curCalc2 = 0
curResult = ((curCalc1 - curCalc2) / 100) * curPercent
Sample results :
Gross : 280 Result : 20.45 I Get : 20.40
Gross : 310 Result : 23.45 I Get : 23.40
Gross : 325 Result : 24.95 I Get : 24.90
Gross : 400 Result : 32.45 I Get : 32.40
Any help will be greeted with open arms!!! :)
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make sure your calculation are done with more than 2 decimals places, and don't round up or down until the very end.
hope this helps
FireBeast
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Cheers for the input, but there are rules to when (in the calculation) you are supposed to round. Thanks anyway. :)
Anyway I have just found out what was wrong. Nothing!
The bleeding NI tables are incorrect and have always been out by about 5p every year. Someone could have let me know that before I started checking all my results against them!! :mad:
