Editing shopify checkout without recreating the whole checkout process

New Member
1 0 1


I'm currently trying to find a way to conditionally edit the tax for the user at the checkout depending on the shipping country. I've looked at tax overrides but they only allow a static value, but do not allow to create a tax that is a percentage of the total if the total of the order is above a certain number.

I was advised that a private app would be the way to go, but going through the shopify api, I cannot seem to find instructions on how to do this without re-creating the checkout. I hope that I've misunderstood the docs and it's possible to do it on the existing checkout by just adding some conditional logic.


Any tips appreciated,


Replies 5 (5)
Shopify Staff
Shopify Staff
497 42 117

Hi Matt,

Not sure I fully understand what you are trying to do, does the Shopify calculated tax not work for your customers?

In any case, the Checkout API allows you to specify tax when you create a checkout, but can only be used if you are building a Sales Channel App.

Another option could be to create an order using the Orders API and specify the tax in the tax_lines order property.

Hope this helps,


Ryan | Shopify 
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New Member
2 0 2

Hello - We want to do something similar - ie. replace the shopify calculated tax with rates we get from external data. We want to do that because the rates that Shopify calculates are not accurate to the tax jurisdiction level. They are calculated by zip code and local tax jurisdictions cross zip codes. Consequently, when we import orders into our ERP - which handles cross zip local tax jurisdictions - the tax data from Shopify does not match. 


So, to summarize, we are looking for a way to intercept and alter the tax calculation. To do so, we need the ship street address city, state and zip to do the lookup against our tax data for the rate and we then would need to inject that into the tax line item in Checkout. Is that doable?




86 4 18

@Coho did you find a solution to this? I am in the same boat and working to build an app that needs to intercept and provide a more accurate tax rate from an external source as the Shopify rate or the AvaTax rate is not sufficiently accurate for my clients. I would be very interested to see if anyone solved this yet. 

New Member
2 0 2
We assume this is doable but did not pursue a solution as the client with whom we were working went with a different solution.
Shopify Partner
14 0 2

@Jroyce1180  Did you find the way to do it?