Does the Customs Duty consider VAT?

I'm buying something from China through Aliexpress, the original price is around 250 pounds, but it's discounted to around 130. Delivery is free. At checkout, it says Aliexpress is required by law to collect the VAT, which is perfectly fine. I'm just wondering if would i need to pay the customs duty since before the VAT i only paid £135. Or does the customs duty add the VAT at checkout with the value of the product.

Hi Yui Joe Cheung,
Anything posted or couriered to you from another country goes through customs to check it is not banned or restricted and you pay the right tax and ‘duty’ on it.
There are certain thresholds which are explained in below guidance:
Tax and customs for goods sent from abroad
Customs charges are applicable based on the total value of the items.
Please check below guidance on how to work out the customs value for Customs Duty, import VAT and trade statistics if you’re an importer or clearing agent.
Working out the customs value of your imported goods
Thank you.