Tax file numbers and super contributions

Calculating interest

The rate used in calculating the interest is set by law and is reviewed every quarter.

Interest on no-TFN-quoted tax offset is calculated as follows:

number of days 365*	X	amount of interest-bearing tax	X	interest rate for period 100
*366 for a leap year

The interest-bearing tax is the amount of tax payable for the no-TFN-quoted contributions income that counted towards the tax offset.

If a payment of interest extends over two or more interest rate periods, you are required to calculate a separate interest entitlement for the number of days within each different rate period that the overpayment attracts interest.

For more information about quarterly interest rates, refer to Interest on early payments and overpayments of tax 2011-12.

Sections within Claiming back additional tax

• Interest on no-TFN-quoted tax offset
• Interest on overpayment
• Evidence required to claim interest
• Calculating interest
• Period of interest