3636742 - When changing tax rate for US external taxes error "External tax system is active, the tax rate must be either 100 or -100" is prompted

When attempting to change the tax rate from 100 or -100 to another value for a tax code which is active in US external tax calculation the error message FOT_COMMON 031 "External tax system is active, the tax rate must be either 100 or -100." is prompted.

SAP S/4HANA Cloud Public Edition 

1. Access configuration activity "Define Tax Codes for Sales and Purchases" SSCUI 101016.
2. Enter Country/Region US.  (Important to note in "Assign Country/Region to Calculation Procedure" SSCUI 101721 the tax procedure 0TXUSX is assigned for US external taxes "Tax USA Jurisdictions (ext.)").
3. Attempt to change the tax rate from 100 or -100 to another value.
4. The error message FOT_COMMON 031 "External tax system is active, the tax rate must be either 100 or -100." is prompted.

All tax code for US external taxes should have a tax rate of 100 or -100.  The tax rate is not calculated by SAP this is determined through the external tax partner.

All tax rates must be 100 for the active tax codes I0, I1, O0, O1, U1 which are maintained for US external tax procedure 0TXUSX.  Otherwise this will cause errors when the tax partner returns the tax rates.

For further details on this please see 2528016 - External US Sales and Use Tax Calculation point 3;

"When external tax calculation is used, the tax rates are automatically determined in transactions based on calls to the external tax provider. When these codes are set up, a tax rate placeholder entry is stored for each tax code, where 100% is stored for each tax-relevant tax condition. This program loads the percentage for each tax code based on the information as returned by your tax provider. Do not change this 100% value. Altering this 100% placeholder results in incorrect calculation or prevents values from being transported. Either outcome leads errors in your reporting."

2528016 - External US Sales and Use Tax Calculation

External Sales and Use Tax Calculation

OBBG, FTXP, US, T007A, FOT_COMMON031, Vertex, thomson reuters, tax calculation, Avatax, OneSource, Business Partner, Customer, VAT,  , KBA , XX-PART-TIF , Tax Interface (USA) , Problem