VAT Tax determination- question about "Requirement" for Table-Is mandatory?

Question

Hi everybody,
I am having problems to determine the appropriate VAT tax percent in some cases in Mexico.
In Mexico for billing at the border with other countries the VAT tax percent is 11% and for billing inside the country the VAT tax percent is 16%. For determine the VAT tax percent the sequence access is MWST and is assigned to the condition type MWST.  For cover the border cases we create a table 989 with the fields: Distribution Channel/Plant and VK11 is fill out with this information. With these parameters is possible to determine successfully the VAT percent of 11% at border sales point.
The problem that I have is related to the u201Crequirementu201D assigned to the table 989: Distribution Channel/Plant. This table has assigned a standard requirement number 7- Domestic Business and when billing to a customer with address of MX (Mexico) as LAND1 at general data section of customer master data, the VAT tax percent of 11% is obtained successfully, because all the fields of the table are filled. But when billing to a customer with address of US ( United States of America) as LAND1 at general data section of customer master data, is not possible to obtain the correct VAT tax percent of 11% even all the fields of the table are filled.
I do not know if the problem is the requirement number 7- Domestic Business, but if I change for the requirement 8- Export Business then the opposite is occurring. For US customers the VAT tax percent is determinate successfully and for MX customers not, because the fields of the u201Crequirement u201Care not filled.  
So, I am wondering if:
1.     Would be necessary to create a new requirement for combine the 7- Domestic Business and 8- Export Business requirements or exist one like this? I do not need to conditioning anything
2.     What happen if I left in blank the requirement field, I mean if I do not assign anything. I was doing testing for both customers and the VAT tax percent was determined correctly. But I do not know if is correct do not assign a u201Crequirementu201D to the table of the sequence of access MWST.
Thank you in advance for your help!

Answer 1

OK I think I understand but here is where I am at now. I originally created a regulation that requires a license when shipping to certain countries out of the EU. I set the regulation as an Export reg did all the necessary config and was able to assign licenses automatically where needed.
Has I was testing the solution I could not find sales docs or deliveries for some of the materials and finally found out they are being moved on NB PO's.
So I changed the reg to include imports etc., classified with import control class etc. but I am seeing a couple things that don't make sense and tells me my config isn't quite right.
I finally do see that the system at least recognizes the new legal reg in the screening now. before this it had not. But it is still telling me it can't find any relevant country.
The other thing the document itself only shows under Display Existing Export Documents even though in the log it says it's an import document and when I go to the Import log there is no data.
Before I realized there was a note to change the Import to export on transfer I assigned the PO types to export orders and I am thinking that's why they are showing in the export list but I woul have tought that it would say it's an export doc which it doesn't.
Any ideas?