Need advice moving mortgage
My partner and I are planning to move to a new location within Netherlands as we are not happy with the current one.
We have a primary residence worth €720k with a €590k mortgage. We have a fixed interest rate of 1.8% interest rate fixed until 2034.
We found that we can move to a house we like better in the €500k–€550k range. Our bank has confirmed the mortgage is "portable" (meeneemregeling).
I am considering selling our current home and buying the cheaper one while "porting" as much of the 1.8% mortgage as possible.
The Math (as I see it):
Selling for €720k minus the €590k debt leaves us with €130k in equity.(Still need to consider selling cost and purchase cost) Let’s say 30k. So leaves me with ~100k
How I plan to use the 100k:
Invest Into a Global ETF (VWRL/IWDA).
The "Arbitrage": Keep the cheap 1.8% debt in while the 100k grows at a (hopeful) 7% in the market.
OR
Do I use that money to pay mortgage for next house?
My Questions:
Taxation: Is there anything I'm missing regarding Bijleenregeling? I understand I lose some mortgage interest deduction (HRA) if I don't put all profit into the new house, but at 1.8% interest, is the HRA even worth worrying about?
Porting: Has anyone successfully ported a mortgage to a cheaper house? Are there hidden traps with risk classes or LTV?
TL;DR: Moving to a cheaper house to unlock €90k equity, kill Indian debt, and invest in ETFs while keeping a 1.8% rate in NL. Is this a good move?