Hi @hary , you are using App10 right? 

What do you have ticked here under Customer Tax? 

My understanding is that, if the object (sales part or sales charge type) is taxable and the tax liability type is taxable, it fetches tax codes from object and CO address. Probably due to that you may have multiple taxes? 

i have address level checked on tax control and when creating a customer order, tax code on sales part and tax code on address  are fetched. so what’is your recommendation? I suggest to not put tax code on sales part, so the defaut tax code address  will be the only one whitch is fetched. 

Hi Hary,
To answer to that question we should thoroughly look at all the options given through IFS App10 Tax Control, which is a great development by IFS RnD compared to previous versions.

You said the Address level is taxable in your case. When Address level is checked, its not mandatory to enter tax codes. However system gives an information message when you are entering a new address. So you may or may not enter taxes at address level even though its checked. When you have multiple tax codes defined there, still the CO lines get multiple taxes in the tax dialog

You also said that your Sales Part / Charge Type is not taxable. Hence it should be possible for you to only enter tax codes with tax types Calculated Tax, No Tax or Tax with 0% there

Is this what you need to achieve?

or

If you want, you can enter a single tax code on the CO line and uncheck ‘multiple tax lines’ check box. Then it overwrites whatever defined at object or address. Isn’t this the option you are looking for? This might not be an option when you have a huge number of CO lines.

Also a point to note is, Tax percentage can be modified if Modified Tax on Transactions % is checked on the Company/Tax control /Sales & Procurement tab.

Also I won’t touch the Tax Calculation structure (a perfect solution to cover tax requirements for customers doing business in countries with complex tax handling) in App10 since you said it doesn’t apply to your case.

All and all, I think its best to have a full view of all the taxes that apply to your case and then look in IFS how to use it