11 CFR § 100.79 - Unreimbursed payment for transportation and subsistence expenses.
(a) Transportation expenses. Any unreimbursed payment for transportation expenses incurred by any individual on behalf of any candidate or any political committee of a political party is not a contribution to the extent that:
(1) The aggregate value of the payments made by such individual on behalf of a candidate does not exceed $1,000 with respect to a single election; and
(b) Subsistence expenses. Any unreimbursed payment from a volunteer's personal funds for usual and normal subsistence expenses incidental to volunteer activity is not a contribution.