I work for a non profit company and I need help with different requests that I receive from IC's.

Anon
You should look at your contracts with these independent contractors. Unless your contracts (or PO/statements of work) require you to reimburse for travel, then you likely don't owe anything. That is what it means to be independent.
It depends on the way you negotiate the contracts.

Thank you Len

We usually only reimburse for significant expenses if, as noted above, it is agreed to in the contract. For example, when an independent contractor is required to travel to another city either by car or by commerical carriers to provide services under the contract. When this is required, we also stipulate in the contract that the travel needs to be approved in writing by the person managing the contract.
If other expenses need to be reimburse due to the nature of the services to be provided, we set a not to exceed limit on theses expenses. Hope this helps.

If the Contractor Agreement does not address the issue, consider amending all existing agreements to specifically lay out your organization's intent. The agreements I use all state that only budgeted expenses with written pre-approval will be reimbursed.

If the contracts are mute with respect to expense reimbursement, you do not owe it. However, it is best to take Robert's advice and explicitly state that expenses will not be reimbursed. Then there is no ambiguity or hassle.