Assuming this a federal grant, 2 CFR 200.448 Intellectual Property, which covers the allowability of patent costs, applies. The regulation does not makes a distinction for provisional patents, so the regulation would apply. If title to the patent or a royalty-free license is required to be conveyed to the federal government, the cost would be allowable when a provisional patent is required in order to secure the final patent. If title or royalty-free license is not required by the federal award, then the cost would not be allowable.