Onetime charge on contract

Joeri

Is it possible to add a one time charge on a service contract, a sort of fee that is only invoiced on the first invoice of the contract.

Example wrote:

The first invoice would look like this:
- Service Item 1, $10,00
- Service Item 2, $15,00
- Onetime charge $30,00

Example wrote:

The second and the rest would look like:
- Service Item 1, $10,00
- Service Item 2, $15,00

Thanks.