Send them an invoice at the new rates and see what happens.

They asked you to start work on the new project and you presented them with your new rates and they were not challenged. I would think they expect you to bill them for the present work you are doing.

You're the only one that knows you and your clients relationship and whether this would be an acceptable approach or not.

It has worked for me under similar circumstances.

>Hi,
>
>I am in the stages of completing a contract for a Client. 2 weeks ago, they asked me to start immediately on a completely different project. I said "sure, but here's another contract, start date effective today" (regardless of when you approve it). The key point for me was more money/day (for many good reasons of course!).
>
>So in good faith I have started the work for them and continue to bill at the original rate of the previous contract, while waiting for them to approve the new contract. It being a big bureaucratic company it won't happen overnight. My intention is to bill them the excess when I get the contract back.
>
>So, was I a goof and should have immediately given them invoices for the new rate (hindsight I know, but would help in future)? Should I wait a bit and say "You've had X weeks to review my contract and still nothing, so I'm going to bill you based on the new contract NOW"? or should I just grin and bear it?
>
>I feel fairly comfortable that the company wants me to stick around (having given me a second contract), but there are some company politics that may affect the decision.
>
>Thanks for any advice.
>
>Blair