ETA (ETPreface?): Nevermind. Contract language turns out to be totally confusing, and I'll only be confident as to what the answer really is after the first payment. I'll bump this up then if necessary...

I’m hoping one of the more spreadsheet-happy math addicts can help me out! I’d like to optimize payback of my soon-to-be land loan, which is for $45,500 at 5.5% (360 day basis, simple interest), fixed for 5 years, at the end of which it’s refixed for another 5 years unless I object, in which case it becomes an ARM. Current 5 year period P+I is calculated at $315.10/ month. Though I’m going to be working on building up a side gig, I’m calculating based on my current information (and very carefully not doing anything new and different to rock the underwriting boat…).

Because I’m self employed, I never know quite how much I will make each month, but calculating on my “safe” baseline number, I can pay the required amount of the mortgage, plus another $300/month. Beyond that, the amount I could have ranges from $0- $1500, or so quoth YNAB reports. I also want to put in at least a greenhouse (future income source, very rough cost estimate of $25k) and a small house (very rough estimate of $45k plus foundation for the finished shell). Depending on what the forester I hire says, I may be able to offset some costs with timber sales (it was harvested in 2013, and I don’t have a timber management plan yet). And yes, like others here, I'm willing to live in a temporary dwelling and build the house last, if needed...

The fly in the mathematical soup comes in here:

If Bank’s loan is prepaid within the first five (5) years, or within any future Fixed Rate Period, <as defined above>, a prepayment premium will apply to the amount being prepaid. The prepayment premium will be 5% of the prepaid amount in the first year of any Fixed Rate Period, 4% of the prepaid amount in the second year of any Fixed Rate Period, 3% of the prepaid amount in the third year of any Fixed Rate Period, 2% of the prepaid amount in the fourth year of any Fixed Rate Period, and 1% of any prepaid amount in the fifth year of any Fixed Rate Period.

This is one of those situations where I know that as soon as I think I have all the logic and calculations down, I’ll find out that I missed something critical. Also, I’m a spreadsheet ninny. Help? Please?

Rys