It's tempting to just walk away — stop invoicing, let the website lapse, move on. For a lot of owners, nothing dramatic happens immediately. The problem is what keeps running in the background while you're not looking.
If you have a Pty Ltd company
A company doesn't stop existing just because it's dormant. ASIC keeps charging an annual review fee every year, whether the company is trading or not. Miss it, and late fees stack on top. Ignore it long enough and ASIC can eventually deregister the company itself — but involuntary deregistration isn't a shortcut worth waiting for: it happens on ASIC's timeline, not yours, and unresolved debts or issues don't disappear with it. Directors can also remain personally exposed for certain unpaid company liabilities (like PAYG withholding and superannuation guarantee amounts) regardless of what state the company is in.
If you're a sole trader
The risk profile is different — you don't have a separate company accruing fees — but your ABN and any GST registration stay active until you cancel them, which means lodgement obligations (BAS, tax returns) keep applying even if the business itself has gone quiet. Missed lodgements attract penalties regardless of whether you're actually earning anything.
The common thread
In both cases, the obligations don't pause themselves — they keep accruing until you actively cancel them, and any debt that builds up in the meantime (fees, penalties, interest) usually has to be cleared before you can close cleanly anyway. Closing properly now is almost always cheaper than closing properly later.