Good question – this situation comes up a lot with property projects. If you originally claimed GST credits on construction with the intention to sell, but later decide to rent instead, the ATO usually treats that as a “change in creditable purpose.” That means you’ll need to adjust and pay back the GST proportionally (often spread over 5 years under the adjustment period rules).

From what I’ve seen, it’s not usually a penalty unless there’s been deliberate misreporting – it’s more about correcting the input tax credits you previously claimed. Best to keep good records and disclose the change to avoid issues.
https://onlinegstcalculators.com/

If you want to run some quick scenarios (e.g. repayment amount if sold in year 3 vs year 5), you can try this GST adjustment calculator: Online GST Calculator – it makes it easier to visualize how much could be owed back.