forms - What is the best way to add a different billing address in a e-commerce website?

I'm a UX designer, actually working on a e-commerce website template.

Here are my doubts :

When users want to buy a product, the moment they are doing the address form, if they want to receive the bill to another address (different than the shipping address), should we put :

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  A checkbox, checked by default on "Same address for billing", and when they uncheck it, users can add the billing address.

  
  



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  An empty checkbox "Add another address for billing", so users check it to add the billing address

  
  


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  A call to action button "Add a different billing address" ?

  
  

Wording is absolutely not done, as you read, but it just to give you an idea of my problematic.

Thanks everybody.