Forum Discussion

wi11iamr's avatar
wi11iamr
Icon for Advocate II rankAdvocate II
9 years ago
Solved

Calculate compound increased fee from initial start date (Power Query)

Hi there,

 

Having the below sample dataset within a query, I have a monthly transaction record for each Contract reference number, along with the contract's initial fee for the fiirst year, and then the percentage escalation that is to be applied year on year.

 

The CalculatedFee column is the one I wish to calculate.

 

I suspect that in addition to using the InitialFee and ContractAnnualEscalation values, I would first need to determine the number of months/years between the TransactionDate and the ContractStartDate.  I'm having a few challenges with this (a Duration.Months function would be nice), however notwithstanding this, I'm at a loss at how to calculate the new compounded fee for each year.

 

ContractRef#   TransactionDate  ContractStartDate  ContractEndDate   InitialFee     ContractAnnualEscalation   (CalculatedFee)

1                      2016/07/01         2016/07/01            2020/06/31             1000                     10%                                     1000

1                      2016/08/01         2016/07/01            2020/06/31             1000                     10%                                     1000

....

1                      2017/07/01         2016/07/01            2020/06/31             1000                     10%                                     1100

1                      2017/08/01         2016/07/01            2020/06/31             1000                     10%                                     1100

....

1                      2018/07/01         2016/07/01            2020/06/31             1000                     10%                                     1210

1                      2018/08/01         2016/07/01            2020/06/31             1000                     10%                                     1210

....

1                      2019/07/01         2016/07/01            2020/06/31             1000                     10%                                     1331

1                      2019/08/01         2016/07/01            2020/06/31             1000                     10%                                     1331

Need Help
  • Sean's avatar
    Sean
    9 years ago
    Calculated Fee = 
'Table'[InitialFee]
    * POWER (
        1 + 'Table'[ContractAnnualEscalation],
        DATEDIFF (
            CALCULATE (
                FIRSTDATE ( 'Table'[ContractStartDate] ),
                ALLEXCEPT ( 'Table', 'Table'[ContractRef#] )
            ),
            'Table'[TransactionDate],
            YEAR
        )
    )

    I had several versions of this - it seems this is the simplest so far!

    Hope this helps! :smileyhappy:

5 Replies

  • Sean's avatar
    Sean
    Icon for Community Champion rankCommunity Champion
    9 years ago
    Calculated Fee = 
'Table'[InitialFee]
    * POWER (
        1 + 'Table'[ContractAnnualEscalation],
        DATEDIFF (
            CALCULATE (
                FIRSTDATE ( 'Table'[ContractStartDate] ),
                ALLEXCEPT ( 'Table', 'Table'[ContractRef#] )
            ),
            'Table'[TransactionDate],
            YEAR
        )
    )

    I had several versions of this - it seems this is the simplest so far!

    Hope this helps! :smileyhappy:

    • CahabaData's avatar
      CahabaData
      Icon for Memorable Member rankMemorable Member
      9 years ago

      a wholly different approach would be to create a new separate table by DISTINCT Year; so there would be 1 record per year.

       

      then calculate the fee as part of this table.

       

      it might be useful in your data model in the long run, and can then also be joined back into your original table if you need the value with each record.

      • Phil_Seamark's avatar
        Phil_Seamark
        Icon for Microsoft Employee rankMicrosoft Employee
        9 years ago
        The separate table approach could be helpful if the interest rate changes. Although you can still handle this with a single table using iterators.
    • wi11iamr's avatar
      wi11iamr
      Icon for Advocate II rankAdvocate II
      9 years ago

      Thanks Sean - I truly appreciate the effort you took in testing different scenarios. Your suggested code works like a charm!