Navision in Australia - GST - chash basis

Dear all,

we are a german company, using MBS Navison 4.01.
Now we are planning to implement Navisin for our Australian sister company.
The australian tax accountants told us that there are two possible ways to handle the value added tax "GST".
1. cash basis - tax is payable when the vendor/customer invoice becomes paid.
2. noncash basis - tax is payable when the vendor/customer invoice is issued.
I think that our german Navision can only handle the "noncash basis" variant as it is the same as in germany.

Does anybody know, if there is a local australian granule for Navision available that can handle the cash basis, too?

Thanks a lot in advance for your answers!
sv.