I too would love this feature. I'm coming from quicken (good riddance!) and loving gnucash. The mortgage setup leaves to be desired. I tried to use the scheme based formula, but you absolutely need to have access to the current balance to be able to have an accurate scheduled transaction. I do overpay my mortgage every month, and this simply can't be put into GC accurately as a scheduled transaction.

I dont sée why this improvement is so unpopular. Actual gnucash mortgage way of doing is totally unflexible. To me, it's thé number one annoyance of gnucash though it ils globally an excellent product.

If you like this feature request, please consider giving your votes instead to "Scheduled Transactions: Extend Formulas"

The above feature request is more general and is not limited to mortgage. It solves many more problems and therefore has also the potential of attracting more supporters.

http://gnucash.uservoice.com/forums/101223-feature-request/suggestions/3166514-scheduled-transaction-extend-formulas

And I must add that some mortgage contracts allow to borrow on your home equity up to the original mortgage amount. Doing so set the balance to a higher value. Depending on how fast you paid so far (by overpayments or by benefying of a lower variable rate), you may either keep the actal payment and stretch your final payment by a couple of months, or boost your payment to catch-up the forecasted end of mortgage.

To acheive this, the loan p+i calculation engine MUST rely on the actual balance of a loan, not a linear payment schedule from the beginning. I get this flexibility with Quicken. Mortgage is a powerful financial tool rather than a simple loan as you normally get when buying a car and can't do anything with your payment other than clearing prematurely the loan.

But don't get me wrong, Gnucash is a worthfull software to consider in replacement of Quicken. It is just lacking a loan engine as flexible as the one in Quicken.