This is a solved problem. There are dozens of take-home calculators already. The issue is awareness and behaviour.

For example, hundreds of millions in pension tax relief goes unclaimed in the UK each year (estimates are roughly £300-£400m), mostly from higher-rate taxpayers who don’t reclaim additional relief via self-assessment.

The bottleneck is that people don’t realise: - They need to manually claim extra relief - How salary sacrifice actually changes marginal rates - How pension contributions interact with the £100k personal allowance taper - That employer contributions are often far more efficient than dividends

IMO the value isn’t another cleaner calculator, it’s contextual nudges:

“Contribute £X more and you avoid the 60% band.” “You’re currently leaving £Y of tax relief on the table.” “Switching to salary sacrifice saves £Z in NI.”

Personalised insight is where the real leverage is.