Plaid Cymru would consider scrapping council tax and business rates if it forms the next Welsh Government.
Plaid leader Adam Price thinks replacing them with a new property tax could fund a 3p income tax cut and £300m a year extra for education.
He said Wales needs to invest more in education.
Mr Price said paying for it with an income tax rise could discourage graduates from returning to Wales after university.
He is seeking to demonstrate the party has bold and distinctive ideas as the Welsh election in May 2021 draws nearer.
According to the Wales Governance Centre council tax currently generates £1.4bn a year in Wales, business rates £1.1bn and each penny of basic rate