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XLeratorDB/financial Documentation

SQL Server IPMT function for odd-first period loans


LIPMT
 
Updated: 31 October 2010

Use LIPMT to calculate the interest payment for a specified payment for a loan or lease. LIPMT calculates the interest payment amount, which will generally be the same as the interest accrual amount, but in some cases involving the US Rule, may be different.
Syntax
SELECT [westclintech].[wct].[LIPMT] (
  <@PV, float,>
 ,<@LoanDate, datetime,>
 ,<@Rate, float,>
 ,<@FirstPayDate, datetime,>
 ,<@NumPmts, int,>
 ,<@Pmtpyr, int,>
 ,<@Per, int,>
 ,<@DaysInYr, int,>
 ,<@FV, float,>
 ,<@IntRule, nvarchar(4000),>)
Arguments
@PV
the principal amount of the loan or lease. @PV is an expression of type float or of a type that can be implicitly converted to float.
@LoanDate
the date that the loan starts accruing interest. @LoanStartDate is an expression of type datetime or of a type that can be implicitly converted to datetime.
@Rate
the annual interest rate. @Rate is an expression of type float or of a type that can be implicitly converted to float.
@FirstPayDate
the date that the first payment is due. @FirstPayDate is an expression of type datetime or of a type that can be implicitly converted to datetime.
@NumPmts
the total number of payments to be recorded over the life of the loan. @NumPmts is an expression of type int or of a type that can be implicitly converted to int.
@Pmtpyr
the number of loan payments made in a year. @NumPmts is an expression of type int or of a type that can be implicitly converted to int.
@Per
the period number for which you want the payment information. @NumPmts is an expression of type int or of a type that can be implicitly converted to int.
@DaysInYr
the denominator number of days to be used in the calculation of the interest amount in the odd first period. @DaysInYr is an expression of type int or of a type that can be implicitly converted to int.
@FV
the future value at the end of the loan. @FV is an expression of type float or of a type that can be implicitly converted to float.
@IntRule
Identifies the loan as conforming to the US Rule (“U”) or the actuarial rule (“A”) regarding the compounding of interest in the odd first period.
Return Type
float
Remarks
·         If @DaysInYr is NULL, then @DaysInYr = 360
·         If @FV is NULL, then @FV = 0
·         If @IntRule is NULL, then @IntRule = “A”
·         @FirstPayDate must be greater than @LoanDate
·         @Pmtpyr must be 1, 2, 3, 4, 6, 12, 13, 24, 26, 52, or 365
·         @NumPmts must be greater than 1
·         @Rate must be greater than zero
·         @DaysInYr must be 360, 364, or 365
·         @PV must be greater than zero
·         @Per must be between 1 and @NumPmts
Example
Calculate the first interest payment for a 50,000, 5-year loan starting on 1 November with payments due on the first of every month. The rate on the loan is 6 per cent.
SELECT wct.LIPMT(
      50000             --Loan Amount
      ,'11/01/2010'     --Loan Start Date
      ,.06              --Annual Interest Rate
      ,'12/01/2010'     --First Payment Date
      ,60               --Number of payments (5*12)
      ,12               --Number of payments per year
      ,1                --Period Number
      ,NULL             --Days in year (defaults to 360)
      ,NULL             --FV (defaults to 0)
      ,NULL             --IntRule (Defaults to 'A' for acturial)
      ) as IPMT
This produces the following result.
IPMT
----------------------
250
 
(1 row(s) affected)
Calculate the last interest payment for a 50,000, 5-year loan starting on 1 November with payments due on the first of every month. The rate on the loan is 6 per cent.
SELECT wct.LIPMT(
      50000             --Loan Amount
      ,'11/01/2010'     --Loan Start Date
      ,.06              --Annual Interest Rate
      ,'12/01/2010'     --First Payment Date
      ,60               --Number of payments (5*12)
      ,12               --Number of payments per year
      ,60               --Period Number
      ,NULL             --Days in year (defaults to 360)
      ,NULL             --FV (defaults to 0)
      ,NULL             --IntRule (Defaults to 'A' for acturial)
      ) as IPMT
This produces the following result.
IPMT
----------------------
4.80915460931035
 
(1 row(s) affected)
Calculate the first interest payment for a 150,000 4-year loan at 12 percent interest using the US Rule made on 13 October with no payments due until 4 January and with payments due every 4 weeks after that.
SELECT wct.LIPMT(
      150000            --Loan Amount
      ,'10/13/2010'     --Loan Start Date
      ,.12              --Annual Interest Rate
      ,'01/04/2011'     --First Payment Date
      ,52               --Number of payments (4*13)
      ,13               --Number of payments per year
      ,1                --Period Number
      ,365              --Days in year
      ,0                --FV
      ,'U'              --IntRule
      ) as IPMT
This produces the following result.
IPMT
----------------------
3710.27179470793
 
(1 row(s) affected)

This is exactly the same as the LPMT amount. The reason for this is that we selected US Rule as the interest rule. The US rule does not permit the compounding of interest, so the entire payment is applied to interest, and difference between the interest accrued for the first period and actual interest payment is deferred into the next period rather than being added to the principal as is done under the actuarial method.
Let’s look at the same interest payment, but this time we will specify the actuarial method as the interest rule.
SELECT wct.LIPMT(
      150000            --Loan Amount
      ,'10/13/2010'     --Loan Start Date
      ,.12              --Annual Interest Rate
      ,'01/04/2011'     --First Payment Date
      ,52               --Number of payments (4*13)
      ,13               --Number of payments per year
      ,1                --Period Number
      ,365              --Days in year
      ,0                --FV
      ,'A'              --IntRule
      ) as IPMT
This produces the following result.
IPMT
----------------------
4093.15068493151
 
(1 row(s) affected)

The difference between the interest payment amount and the payment amount under the actuarial method is added to the principal, resulting a negative principal payment in the first period, increasing the outstanding principal balance.
If you don’t know the period number that you want, you can use the NPNO (Next Payment Number) or PPNO (Previous Payment Number) functions to calculate the period number.
In this example, we calculate the current period interest for a 50,000 5-year loan on 10/31/2010, which originated on 9/15/2008 at a rate of 5.5% with monthy payments commencing on 10/15/2008.
SELECT wct.LIPMT(
      50000             --Loan Amount
      ,'09/15/2008'     --Loan Start Date
      ,.055             --Annual Interest Rate
      ,'10/15/2008'     --First Payment Date
      ,60               --Number of payments (5*12)
      ,12               --Number of payments per year
      ,wct.NPNO(
            '10/31/2010'      --Settlement Date
            ,'10/15/2008'     --First Payment Date
            ,12               --Payments per Yer
            ,60               --Number of Payments
            )           --Period Number
      ,365              --Days in year
      ,0                --FV
      ,'A'              --IntRule
      ) as IPMT
This produces the following result.
IPMT
----------------------
141.252098513512
 

(1 row(s) affected)



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