GST is calculated differently on Customs payments. The GST portion of the item purchased is charged separately to the item itself, and is charged along with the other Customs duties and fees. This is for high value items (over $1000) that will be used for business purposes.
See here how to handle this in Focus:
1) Record a Money Out Invoice for the payment (Attach the original invoice)
The Payment Request form shows the charges and fees as well as the GST portion for the item purchased as follows:
2) Select GST inclusive option in the Line amount and Record the separate lines as they appear in the invoice, except for the GST amount. These lines are usually coded as Admin.
3) Correctly select the GST coding for each line to Exempt or Business dependent on the charges
3) To record the GST on the purchased item and ensure that it is 100% coded to GST for your GST Returns, add two more lines. The first you will include the total item cost inclusive of GST, in this case $69,816.50, and code this as a Business expense. This will calculate a GST portion of $9,106.50.
The second line will be a contra (positive) entry, of the item amount exclusive of GST and coded as Exempt so that this does not alter your GST Return.
4) Check that the correct GST amount has been calculated in line with the Customs Invoice and Select Save.
For more information on Customs charges or to calculate your GST and duties, use the "What's my duty" Calculator or visit Customs.govt.nz