Offset vs Shares Calculator 2025

Should you keep your cash in the mortgage offset or invest in shares? Model the real cashflows: dividends (with franking), capital growth, yearly sales to fund extra interest, and CGT on every sale.

Base case: Leave money in the offset
“Amount kept in offset, earning its effective return by reducing interest at this mortgage rate over this time period”
Your tax settings
Pull money case: Invest in shares
“If I invest the offset money, here’s the dividend and growth I expect.”

When does investing beat the offset account?

This calculator mirrors real life: if you pull money out of your offset, your mortgage interest bill rises. Each year we use after-tax dividends (including franking credits) to cover that bill first, then sell only the required amount of shares to fund any shortfall (paying CGT on those sales). Any surplus dividends are reinvested. At the end, we liquidate the portfolio and apply CGT so you see the actual cash left in your pocket.

Tip: try a fully-franked dividend ETF vs a low-dividend global ETF and see how the yearly sales (and tax) change the outcome.

Disclaimer: This tool provides general information only and does not account for your personal objectives, financial situation or needs. Tax rules can change and individual circumstances vary. Consider seeking independent advice. See our full disclaimer.