When you check the box to mark the invoice as tax inclusive you don’t see a separate line for VAT. Instead, you should see a line after the total saying how much VAT is included. Read this Guide: Choose between tax-exclusive and tax-inclusive prices | Manager
Hi I think you are making some mistakes in using the VAT-codes.
When you sell services or goods to some in the Netherlands, you should use the in-built tax-code BTW 6% and BTW 21%
The VAT codes 21% EU and the other EU VAT codes should only be used when you export or deliver goods to a non-Dutch business. You are only allowed to use these codes when you have the VAT registration number of your customer in his home-country, For non-business customers outside the Netherlands, you have to use the Dutch VAT codes 21% BTW and 6% BTW
The concept BTW-aangifte works only with the in-built tax-codes.
In case you need further help in setting up your business, you can send me a private message.