Getting an error while posting GL A/c i:e FSOO.
The Error is "Company code not assigned to country or country to calculation procedure".

Do the Following Customisation :

Step 1: Check Calculation Procedure
IMG >Financial Accounting>Financial Accounting Global Settings >Tax on Sales/Purchases>Basic Settings >Check Calculation Procedure 

Tax procedures are available in SAP for most of the countries. In case a tax procedure is not defined for your country proceed as follows:

In this go to Define Procedures Check for TaxINJ or TaxIN 

If it does not exist create a new one by copying it from TaxGB

Step 2: Assign Country to CalculationProcedure
IMG >Financial Accounting>Financial Accounting Global Settings >Tax on Sales / Purchases > Basic Settings >Check Calculation Procedure 

In this step we assign the calculation procedure created in the earlier step to the country. The country is the country of the company code.

If you are living in India, then your country of the company code is India. 

Step 3. Define TaxCodes for Sales and Purchases
IMG>Financial Accounting>Financial Accounting Global Settings >Tax for Sales and on Sales/Purchases >Calculation>Define Tax Codes

Update the following:- 

Define two Zero Tax Codes input and Output Tax codes.

Go to OB40 Transaction code and Assign GL Account.

Do this your problem will be solved.

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