Setting up GST/VAT

Consumption taxes like GST and VAT can have a material impact on forecast cashflow, so it’s important to set them up the right way. Castaway includes a range of flexible settings to help you model the calculation and payment of GST/VAT.

Setting up GST/VAT in Castaway involves 3 steps:

  1. Set the standard rate and calculation method
  2. Set the lodgement and payment timings
  3. Set the GST/VAT rate for each element

1. Set the standard rate and calculation method

To access the Taxes setup screen in an existing forecast, go to Data > Forecast Options > Taxes. When setting up a new forecast, Taxes settings are on the third setup screen:


Set the Standard GST/VAT rate. Note that this rate will be applied to every element by default, but can be adjusted for each individual element.

Next, set the GST/VAT Calculation Method. Choose between:

  1. Accruals (default): GST/VAT Liability is recognised based on invoice timing, not payment
  2. Cash:  GST/VAT is accrued based on invoice timing, but GST/VAT Liability is recognised based on payment timing


2. Set the lodgement and payment timings

Open the GST/VAT Payments element located at the very bottom of the Castaway Chart of Accounts.


From this screen, you can control settings for:

  1. How frequently GST/VAT returns are lodged with the relevant revenue authority
  2. The timing of payments or refunds arising from those returns

GST/VAT Lodgement Method

Choose between:

  1. Calculate - Castaway will calculate the amount owing or refundable for each GST/VAT return
  2. Manual Entry - enter the values of each GST/VAT return yourself

GST/VAT Lodgement Schedule

  1. Set the frequency of GST/VAT returns
  2. Choose between Monthly, 2 Monthly, 6 Monthly or Annual cycles

Cycle End Month

  1. Select any month that is the end of a lodgement cycle
  2. Note this is the month your return cycle ends, which may be different to the month when you actually lodge the return and pay the amount owing or receive the amount refundable

GST/VAT cashflow timing

Use the Days Credit data entry row to specify the payment terms for each return to be lodged.

 For example:



New Zealand

United Kingdom

Lodgement Schedule


2 Monthly (odd cycle)


Cycle End Month
(choose any of the listed months)

March, June, September
or December

January, March, May, July,
September or November

As appropriate

Cashflow Timing

Generally 28 days
58 for December

Generally 28 days,
45 for November

37 days


3. Review the GST/VAT rates for each element

GST/VAT rates apply to 5 types of element in Castaway:

  1. Sales
  2. Costs
  3. Inventory
  4. Fixed Assets (Tangible)
  5. Fixed Assets (Intangible)

If you identify any elements that need a GST/VAT rate different to the Standard rate, you can:

  1. use the Forecast Designer to change rates for multiple elements from one screen, or
  2. go into the Settings tab in the Element Properties screen of each element one by one
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