TPL -- although I like the idea of paying the mortgage down here are some numbers I got from my bank.
Starting now if in one year I would pay $9,400 in interest. Putting a lump sum down on the mortgage (I asked about putting $20,000) would change that interest charge to $8,000 for the year. It would also change my amortization from 16.7 years to 15.3 years.
You see that's not that great really. Now your other theory about putting that in RRSPs and taking the tax deduction and putting it in the mortgage. That is a GREAT idea except.... according to my calculations this year I will owe ~ $17,000 in taxes to the government. So if I were to put the $20,000 in RRSPs I won't get anything back, I will have less tax to pay on the other hand, so I could do something like, put $15,000 in RRSP take that tax savings ~$5000 and put that on the mortgage.
Still using my $20,000 and paying the gov $12,000 instead of $17,000. I'll have to do the math on that one.