You submit information regarding funds needed for contract services during Phase I of Budget Prep.
If you have a contract that you renew from year to year, and you anticipate the amount needed to pay that contract will increase, the best time to request that increase in your budget is during Phase I of Budget Prep. Similarly, if you have a contract that has ended and will not continue into the next fiscal year, a good time to communicate that to the Budget Office is during Phase I of Budget Prep.
Make sure you have funds in place before trying to pay a contract! - Just because you have a contract that has been signed by the provost does not mean the money has been put into your budget to pay for the contract, unless you took steps to put it there. If you do not already have the money in your operating budget (9300's), you may have to request it during Phase I of Budget Prep, or you may need to ask for an allocation through the operational request process.