The domestic reverse charge (referred to as the reverse charge) is the new way VAT is being collected. There are things you need to add to the invoice. Some of them are:
Details required on a VAT invoice
A note to inform the customer that the domestic reverse charge applies.
Clearly state the exact amount of VAT due under the reverse charge.
If you haven't yet, you'll want to customise your invoice template. Also, the VAT amount should not be included in the total amount due since the customer is the one to pay it.