Tax calculation when matching a receipt to invoice

Hi,

I created a PO with tax 18%. For my supplier the tax is 0%.

After receiving the PO and when matching the receipt to my invoice i get this details:

- In invoice line, the tax classification code is 0% (defined in the supplier"TAB tax and reporting"

- The system calculate the tax with 18% as code- In the invoice tax details, i get the tax classification code as 18%

Is it a standard behaviour

Thanks

Mohamed