Wrong base amount of taxes in OpenERP 6.1

[Alexis de Lattre]

Anevia has discovered that OpenERP 6.1 doesn't compute correctly the "base" amount of taxes ; as surprising as it may seem, the tax amount is correct.

This bug is present in OpenERP 6.1 (not in OpenERP 6.0) with an up-to-date codebase.

Here is a detailed scenario to reproduce the bug :
1. Create a new DB with demo data
2. Install the module "account_accountant"
3. Activate "Extended view"
4. Create a new customer invoice for the partner Agrolait in EUR currency
   Add an invoice line with :
   - Product = HDD1 (could be any)
   - Quantity = 100
   - Unit price = 0.56
   - Discount = 15%
  (if you have a tax, check that it's NOT a "tax included" one)
5. Click on compute tax : you will see that :
  * The total untaxed amount of the invoice is 47.60
  * At the bottom left, in the invoice tax lines, there is one line ; in this line, the "base" amount is 48.00 !
  => These two amounts should be identical ; that's the bug.

The cause of the bug is the following :
* the "price_subtotal" of the invoice line is computed that way :
  1. (quantity * unit price) * (1-discount/100) = 47.60000 (cf line 1272 of account_invoice.py)
  2. Round at the precision of the EUR currency = 47.60 (cf line 1277 of account_invoice.py)

* but the "base" amount of the invoice tax line is not computed the same way :
  1. price_unit * (1-discount / 100) = 0.47600 (cf line 1588 of account_invoice.py)
  2. Round at the precision of the EUR currency = 0.48 (cf line 1589 of account_invoice.py)
  3. Multiply by the quantity : 0.48 x 100 = 48.0 (cf line 1596 of account_invoice.py)

I have written a patch that makes OpenERP compute the "base" amount of invoice tax lines with the same method as the "price_subtotal" of the invoice line. I enclose the patch to this bug report.

In fact, this bug was introduced in the branch addons-6.1 by the commit 5569 dated 2011-11-10, cf http://bazaar.launchpad.net/~openerp/openobject-addons/6.1/revision/5569. This commit was designed to fix this bug : https://launchpad.net/bugs/887367. I have tested the scenario of this bug report to see if my code re-introduces this bug ; it's not the case.

[Fabien (Open ERP) (fp-tinyerp)]

merged in trunk.
Thanks for the very good contribution :)

[Fabien (Open ERP) (fp-tinyerp)]

r7646

[invitu (invitu)]

It does not seem to be merged in lp:openobject-addons/6.1

[Alexis de Lattre (alexis-via)]

I confirm that the fix is NOT MERGED in addons/6.1. The status "Merged" on the merge proposal is WRONG !

[Rifakat Husen (OpenERP) (rha-openerp)]

Hi,
This is yet to merge with 6.1, we will do it soon.

Thanks,
Rifakat Haradwala

[Manu (manu-tiedra)]

I'm amazed this has not been merged yet.

A customer called us pointing out the bug after having sent more than 400 invoices with invalid data...

[cubells (cubells)]

Why has this patch not been merged yet?

It's a serious bug because the tax base of the invoices is wrong calculated.

Please merge now!

[Alexis de Lattre (alexis-via)]

The bug is still not fixed in the official addons/6.1 branch.

But the bug is fixed in the "OCB 6.1" branch (OCB = OpenERP Community Backport) :
lp:ocb-addons/6.1

To get more info about the OCB branches, read https://launchpad.net/ocb-addons