Imports System

Public Module Module1

    Public Sub Main()

        Dim dataInicio = new Date(2015,1,31)

        Dim dataFim = new Date(2015,2,28)

        Dim dias = Dias360(dataInicio, dataFim)

        Dim meses = Meses360(dataInicio, dataFim)

        Console.WriteLine("Dias entre  " & dataInicio & " e " & dataFim & ": " & dias)

        Console.WriteLine("Meses entre " & dataInicio & " e " & dataFim & ": " & meses)

    End Sub

    Public Function Dias360(dataInicio As DateTime, dataFim as DateTime) As Integer

        Dim diaInicio = dataInicio.Day

        Dim diaFim = dataFim.Day

        Dim mes = dataFim.Month - dataInicio.Month

        Dim ano = dataFim.Year - dataInicio.Year

        If diaInicio > 30 Then

            diaInicio = 30

        End If

​

        If diaFim > 30 Then

            diaFim = 30

        End If

        Return (diaFim - diaInicio) + mes * 30 + ano * 360

    End Function

    Public Function Meses360(dataInicio As DateTime, dataFim as DateTime) As Integer

        Return Math.Truncate(Dias360(dataInicio, dataFim) / 30)

    End Function

End Module