If your tax return is amended and there is a tax shortfall, we apply SIC rather than general interest charge (GIC). This is because taxpayers are usually unaware of a shortfall amount until they receive an amended assessment.
We apply SIC to the tax shortfall amount for the period between when it would have been due and when the assessment is corrected.
We update the SIC rate quarterly using a formula set by law.
SIC applies to amended assessments for:
- income tax for the 2004–05 and later income years
- petroleum resource rent tax for the 2006–07 and later income years.
SIC is applied on a daily compounding basis to the shortfall amount.
The due date for payment of the extra tax and SIC is 21 days after the day we issue the notice of the amended assessment. Once the due date has passed, GIC will apply automatically to any unpaid tax and SIC.
You can claim a tax deduction for SIC in the income year that you receive the notice of assessment that includes the SIC amount.
If we remit SIC, you must include the remitted SIC amount as interest income in your tax return in the income year that we granted the remission.
If you make an amendment that reduces an earlier amendment, you must also include the amount of SIC that was reduced.
You can ask us to remit SIC amount (and any related GIC) in full or part if there are extenuating circumstances – for example, if we contribute to an error that leads to a shortfall, or if the shortfall amount is paid before the notice of amended assessment issues.
For more information, see PS LA 2006/8 Remission of shortfall interest charge and general interest charge for shortfall periods.Shortfall interest charge may apply if your tax return is amended and your tax liability increases.