[GNC] Stumped on Mortgage Asst - Screenshots

Wed Aug 3 14:54:16 EDT 2022

On 8/3/22 05:37, steve.schwandt at fastmail.com wrote:
> Thanks for the background folks. I appreciate the effort and will do 
> the manual creation.
>
> However, I'm hardheaded enough that I want get the transaction to work 
> within tolerances with a minimum of monthly intervention such as 
> editing or reading bank statements. I have to go on record that P&I 
> for July 2022 and May 2035 is more than simply fractions of pennies 
> from various calculation assumptions. I don't need that sort of 
> precision in tracking trends in my personal Net Worth reports.
>
> Is there a man page of sorts for the various functions, pmt, ipmt, 
> ppmt?  I'm sure one of the trailing zeros refers to whether payments 
> are due at the beginning or end of the period, but can't imagine what 
> the other may be. Meanwhile, I'll continue experimentation on my dummy 
> data. Like I said, hardheaded.
>
> Steve

I found the details buried in the code.  Look in these two source code 
files:
./libgnucash/app-utils/calculation/fin.c
./libgnucash/app-utils/fin.scm

The '.' for me is at /home/steve/Projects/GnuCash/gnucash

where 'gnucash' is my copy of the git repository.
>
> On 8/2/22 10:17, David Carlson wrote:
>> Steve,
>>
>> I am not going to open your zip file, I imagine it is just 
>> documenting the
>> fact that the P & I calculations don't exactly match your lenders'
>> statements, which is a known issue, unfixable since they all have 
>> their own
>> way of calculating it.  At least that was the case years ago when I last
>> set one up.  Many of us, like Will, just accept the numbers as estimates
>> and correct them when we get the statements.
>>
>> There has been some discussion in the history here about how to 
>> massage the
>> equations when we want to 'start in the middle' for an existing loan, 
>> for
>> example, but I am not sure how to find those.
I have done that to start a year in and to include extra $ for 
principle.  It is best to use LibreOffice Calc (Or Excel) to calculate 
the monthly payment and number of months needed to fit your situation.  
It has been several months and one of my loans is spot on each month.  
The other one -- well, I'm wondering what the bank is smoking as it 
flops around by a significant amount each month.  I suspect they are on 
a daily interest amount and since the number of days between payments 
varies (US mail, # of days in month, pay early/late by a day or so) they 
come up with numbers that make my head spin.

So, as some have suggested, I just wait for the statement to come out 
and then I adjust the posted transaction.  at least the payment amount 
totals the same each month!

Here is the setup for my recent mortgage:

The 1326.35 is my total monthly payment.
.02990 is my annual interest factor.
i is the internal counter for the month of the loan.  GnuCash controls 
that number
360 is the total number of payments.
315,000.00 is the original loan amount.

Here is the one for my 5th wheel where some interest was prepaid up 
front and they delayed the first payment so I'm adjusting the month 
counter by -2 to get the numbers to be close enough.  This is also the 
one where I suspect they use a daily interest amount rather than 
standard calculation as the numbers bounce around each month.

I have cc'd you direct just in case these two images being pasted 
directly in don't make it via the list.
>>
>> On Tue, Aug 2, 2022 at 8:47 AM William Prescott<will at theprescotts.com>
>> wrote:
>>
>>> A slight variation on Steve's suggestion.
>>>
>>> I made the mortgage payments a 'Scheduled Transaction' with some 
>>> nominal
>>> values for principal and interest payments. Then, they were created
>>> automatically, and I just edited them to get the amounts correct.
>>>
>>> Will
>>>
>>> On 2022 Aug 2, at 08-02 02:55:33, David T. via gnucash-user <
>>> gnucash-user at gnucash.org> wrote:
>>>
>>> Steve,
>>>
>>> I expect others will give you ideas on how or what is mistaken on the
>>> mortgage assistant.
>>>
>>> I, however,  am going to suggest a different approach, which is to 
>>> forego
>>> using the scheduled transactions/mortgage assistant altogether, and 
>>> simply
>>> enter the monthly payments manually.
>>>
>>> The reason I suggest this is due to the fact that (as Michael Novak 
>>> often
>>> reminds us on the list) your calculations and the bank's 
>>> calculations will
>>> likely not match precisely, due to differences in base assumptions 
>>> on the
>>> calculation. Because they won't match precisely, you'll end up 
>>> editing the
>>> completed transactions. [For this reason, I truly wonder whether the
>>> mortgage assistant is actually useful or should be included in the 
>>> program,
>>> since it seems to cause more troubles than it solved. That's just my
>>> opinion, however.]
>>>
>>> If, instead, you enter the transactions manually, Gnucash will autofill
>>> the transaction with the last entered values, and you can quickly 
>>> modify
>>> the amounts to match the bank statement.
>>>
>>> David T.
>>>
>>>
>>> On August 1, 2022 11:59:06 PM 
>>> GMT+03:00,"steve.schwandt at fastmail.com"  <
>>> steve.schwandt at fastmail.com> wrote:
>>>> All,
>>>>
>>>>      Please help if you can. I think I've documented with the shots
>>> required, but if you want to see something else, sing out. Somewhere 
>>> I am
>>> missing a very basic concept. I'm trying to use the assistant to 
>>> create a
>>> scheduled transaction. The file names describe each step. The file 
>>> and CoA
>>> are dummies until I grasp this concept and move on to putting my 
>>> 401kk of
>>> MUFUs into the tool.
>>>> - I've used my current statement, due 1 July to match up a 
>>>> amortization
>>> website to show the P&I due on 1 July. Amounts and start dates in the
>>> assistant are configured to match those amounts. Curiously, the 
>>> website and
>>> my statement show a different remaining balance, but that is outside 
>>> the
>>> scope.
>>>> - I step you through my assistant.
>>>>
>>>> - In the end I show you the result of the assistant, which shows the
>>> correct P&I. Escrow is wrong, but I'm sure I can fix that in the 
>>> editor.
>>> I'll accumulate escrow each month and then schedule a payment from 
>>> escrow
>>> asset to tax and insurance expenses once all the above works.
>>>> - I let GnuCash enter the created transaction (ignoring from birth of
>>> the loan) and the transaction for 1 July 2022 is actually the P&I 
>>> for 1 May
>>> 2035.
>>>>
>>>> TIA
>>>

-- 
Stephen M Butler, PMP, PSM
Stephen.M.Butler51 at gmail.com
kg7je at arrl.net
253-350-0166
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