According to the ATO, to be eligible for a tax offset for franking credits you are required to hold the shares 'at risk' for at least 45 days (90 days for preference shares and not counting the day of acquisition or disposal).
If you do not satisfy this rule:
- you’ll be denied the benefit of any franking credits attached to dividends received.
- you won’t be required to gross up your assessable income to include the denied franking credits in your income tax return
- you won’t be entitled to claim the denied franking credits as a tax offset.
As a result, you’ll only be subject to tax on the cash amount of the dividend received in respect of that particular parcel of shares to which the denied franking credits relate.