More than 2 million Australian investors holding property and private business interests are facing significant new compliance costs under revised capital gains tax regulations.

The Australian Taxation Office (ATO) has warned that these investors will need to pay for professional asset valuations, with fees running into the thousands of dollars, to ensure accurate reporting under the new regime.

The shift marks a tightening of enforcement standards for non-listed assets, moving away from informal estimates toward formal, auditable valuations.

For retail investors and small business owners, this introduces a direct cash outlay that was not previously a standard part of annual tax compliance.

The ATO has indicated that failure to provide robust valuation evidence could trigger disputes and further penalties, raising the stakes for accurate reporting.

This development adds to a broader trend of tax authority scrutiny on private wealth and property holdings.