Instead of creating invoices for the full amount you are due, you can always create invoices with only an arbitrary part of that full amount.
You can issue partial invoices the same way as normal invoices. Head either to Billing > Invoices, to an individual project in the Invoices tab, or to an individual budget by clicking on the NEW button.
You can read more about creating invoices in general here.
When you create the invoice, you will be able to edit its data, such as the service type, description, unit, and quantity. Here, we are primarily concerned with the quantity.
You create a partial invoice by reducing the quantity of a line item (e.g. hours) on an invoice. By doing this, we are invoicing a reduced amount, the remainder of which we can invoice later on, as described below.
For instance, we can remove 2 hours of the Web development service from the invoice above, thus bringing its quantity down from 20 to 18 hours.
The invoice amount will be proportionally reduced, and we can invoice these two hours that we've removed from the service at any point in the future.
You will also be able to change data about an invoice at any later point through Billing > Invoices, as long as you have not sent the invoice:
If you want to change other data about an invoice, be sure to read this article first. Note that you will not be able to change multiple line items at the same time. Additionally, prices for individual line items may not be reduced as a percentage of the total amount.
Furthermore, if you'd want to find out more about creating advance payments in Productive, we recommend you take a look at this article.