You will have to provide evidence to them of you no longer trading and when the business folded. You are only liable to keep your records for 5 years.
There was no BAS to be lodged in the 1990's the GST came in in 2000.
If you did not lodge returns there is no limitation period and they can sue you.
If you have lodged them, you advise them that it was lodged and if you had an accountant assist you then he can deal with this.
The limitation period applies if you owe them money and have lodged the return and they issued an assessment. If you had not lodged any returns then there is no limitation period.
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