Comment 7 for bug 1155606

Hello!

I checked once more, I agree with Quentin (OpenERP). This is typical situation for us as well for VAT reporting, when credit/debit=0 and tax_amount has value e.g. they do not have the same value.
BUT WE HAVE ONLY cases when credit and debit=0 and if tax_amount is negative for Refund invoices.

What I pointed out there are situations when OpenERP cannot handle taxing and accounting right an cause what you mentioned.

I was not may be clear, so will try to explain in detail, cause this is generic thing:

- First issue is not directly related, but OpenERP cannot handle correct VAT report, when we do not know exact VAT base amount at invoice creation time and it doesn't match to invoice totals, because for import operations VAT base
is calculated not from invoice itself, but unknown value determined by toll procedures.

- Second issue is an example how to get wrong results in taxing and accounting.

Your company currenccy is EUR, you use automatic currency rates import into OpenERP from legitimate authority.

1. Purchase Manager issue Purchase Order 100GBP and Supplier Invoice is generated automatically on 1th March. Supplier Invoice is generated in currency with floating currency rate (GBP, USD, JPY etc.)

Note, that invoice is generated automatically and is in DRAFT state (NO INVOICE DATE SET)
In this case:

* Invoice is 100GPB and VAT should be accounted (cause GB is EU member)
* account.invoice.tax object is generated and currency conversion is performed on 1th March (date of invoice creation!!!)
* field base_amount is 115.36 EUR (based on 1th March currency rate!!!)

Total invoice sum in foreign currency (GBP) is correct.

2. After one week Purchase Manager receives goods and finish encoding the invoice.
Note, that supplier shipped goods NOT on 1th March, but let's say on 4th March and issued invoice dated 4th March

In this case:
* Purchase manager enters valid invoice date. 4th March
* Purchase manager enters invoice number in description
* Purchase manager confirms Supplier Invoice by pressing "Validate" Button
* account.invoice.tax object remains INTACT, because it is already calculated !!!
* acount.move.lines are created (currency conversion for accounting move lines performed by invoice date 4th March!!!)
* field base_amount is 115.36 EUR (REMAINS THE SAME AS ON MARCH 1th)
* account.move.lines debit or credit entries are calculated from base_amount 116.05 (AS ON MARCH 4th)

The result is difference 0.69 EUR in tax base_amount between tax reports and accunting on 100GPB invoice.

We solved this situation in OpenERP ver.6.0 by adding constraints of catching such differences while validating the invoice, but allowing if specific circumstances are met for correct VAT output.
When you press "Compute Taxes" base_amount and related tax fields are recalculated and become correct.

Normunds
Alistek Ltd