Australia’s biggest business groups warn of an increasingly unpredictable tax system as the backlash against the capital gains tax overhaul continues.

Non-tech business owners fear being left out of any government carve-outs of the budget’s much-maligned capital gains tax changes.

Start-up founders say the federal government's CGT changes may see investment in new businesses go offshore. But Airtree Ventures co-founder Daniel Petre is warning against a…