While driving for business is deductible, that doesn't include the cost of commuting to work. The same logic applies to parking. If, say, you pay to leave your car in the parking garage next to your office, there's no write-off. Leave your office or home office to visit a client or a job site, though, and any parking fees at your destination are deductible. If you're self-employed, you can deduct the parking fees against your business income.
If your employer reimburses any of your parking costs, this probably doesn't count as taxable income. However you can only deduct parking expenses when there's no reimbursement. Employee expenses are a "2 percent" itemized deduction, like union dues and professional licenses are. You add up all such expenses, subtract 2 percent of your adjusted gross income and write off whatever remains. If you take the standard deduction, you can't write off work-related parking.
If you run up parking expenses while you're volunteering for a charity -- picking up donated goods or helping with a charity auction, say -- those costs are deductible. You can claim the write-off if the charity qualifies to receive tax-deductible contributions, but this is only an option if you itemize deductions. Parking costs while you visit a doctor are usually deductible as part of the itemized write-off for medical expenses. Add up all your deductible expenses, then subtract 10 percent of your AGI. Whatever remains is your write-off.
Rather than figure the actual cost of driving your car for charity or business, the Internal Revenue Service lets you claim a straight per-mile deduction. Even if you don't use actual costs, the IRS still allows you to deduct parking in addition to the per-mile write-off. You will need to keep records of where and when you parked, why you parked and how much you paid. If you can show a regular pattern -- you park at the same hospital once a month or visit the same clients every week -- the IRS will probably accept the write-off without a parking receipt from every visit.