Check the contract for clauses about key personnel. Some contracts prohibit the replacement of key persons to project work without prior authorization of the contracting office. Many contracts prohibit overtime or compensatory time without the prior written authorization of the contracting office. Some contracts have security restrictions. Even certain civilian contracts contain confidential business information or data subject to the Privacy Act.
Some contracts have special billing instructions.
Be prepared to explain it to your government project officer. You are responsible for gaining the government project officer's approval and sign-off on the monthly voucher. Please make certain that this happens within several days. Monitor options to renew or extend the contract. Make certain the government exercises these whenever possible.