automatically balancing Scheduled Transactions

[Phil Frost]

On Sat, Jan 15, 2011 at 11:40:56PM -0500, J.P. Lien wrote:
> I'm trying to set up a scheduled transaction for my mortgage payment.  I
> used the druid, but had to make some changes to the template transaction
> (I've paid extra on the loan in the past, so the ppmt function doesn't
> return the right value).  When I was done I got the following warning:
> 
> "The Scheduled Transaction Editor cannot automatically balance this
> transaction. Should it still be entered?"
> 
> I guess this is telling me that the editor can't verify that the
> transaction will balance every time.  It should be balanced based on the
> way I entered it, but I can see how it would be better to make certain.
>  Is there some magic variable that I can put in to capture any imbalance?

It's telling you this probably because the template transaction contains
variables (like i). There's no reasonable way for the transaction editor
to know that the transaction will balance for all values of i, since it
doesn't know what the functions (probably pmt, ppmt, ipmt in your case)
do.

To test such things, I found it helpful to save my file, then change the
SX to be created 365 days in advance. Run "Actions->Scheduled
Transactions->Since Last Run..." and check "Review created
transactions". Then you will get to see all the scheduled payments for
the next year, and if they balance. Quit without saving.

There is not, to my knowledge, any way to capture any imbalance.
Instead, it will go to the imbalance account as usual. Hopefully the
functions are designed such that this doesn't happen. For example, it
should be that ppmt + ipmt = pmt.

If you have made additional payments to your loan in the past, and if
your loan is like mine and the monthly payment does not change even if
you did so, you may find the *pmt functions do not provide any way to
accurately describe your loan. I recently dealt with a similar issue,
and my solution is described here, along with the problem in more
detail:

http://lists.gnucash.org/pipermail/gnucash-devel/2011-January/030790.html