I've got the steps to help you set up IRPF and IVA for the same product, alicia. 

No worries, this is quick and easy. First, we have to create IRPF and IVA and combine them. 

Then, we merge the mentioned taxes. To do that we can:

1. Go to Taxes, and select Add tax.
2. Choose the Group rate option. 
3. On the Tax rate dropdown lists, hit IVA and then IRPF. 
4. Click Save.  

Second, we can assign these taxes to our products and services. 

Here's how:

1. Go to Products & services. 
2. Choose a product type. 
3. Key in the necessary information. 
4. On the Tax dropdown menu, select combined tax rates. 
5. Hit Save and close. 

I'll add this guide for more info: How do I set up sales GST/VAT rates and use them on forms? (International QBO)? 

Moreover, you can visit this article to learn more about modifying tax rates: Edit tax rate in QuickBooks Online.

Hit the Reply button if you have more questions about managing taxes. I'll circle back to assist you. Take care always!