Input1 was 135k mortgage @ 2.25% for 35 years @ 43% tax bracket with an additional 300/month cash redirect. Investment return was 8%, and the motgage was gone after 16.5 years.

Portfolio was 1.2 million after 16.5 years.

Input 2 was 135k mortgage @ 2.25% for 18 years (making monthly payment = input 1 mortgage payment + 300 redirect).

Mortgage was also gone after 16.5 years, BUT the portfolio was only worth 247k assuming the same 8% return.

The monthly payments were almost identical, but the interest costs were 1/2 with the initial shorter mortgage, thus giving me 74k LESS in tax deductions.

The principal with the 300 redirect was in linbe with the principal paydown with the shorter mortgage.

I am just having a hard time wrapping my head around an almost million dollars difference after 16.5 years.

How can this be explained? Can 74k in tax deductions make a million dollars of difference?

Cannon, if you are out there , you are a numbers guy. Maybe you could explain this a bit?

I am trying to figure out if I should divert a monthly RSP into a SM top up.

For the same monthly cash flow I would rather have 1.2 million than 247k.