Answer: First, let’s make sure you’re talking about an event of a Qualified Organization (QO) — if this wasn’t a QO you don’t get to deduct anything.
Next, you have to look at the value of the meal, entertainment and other benefits you received for attending. If, for example, the value of those benefits was $70, you get to deduct $50 — the price of the ticket minus the value of benefits you received. This is true, even if the ticket says the $120 was a “donation.”
This treatment arises under what are called the IRS quid pro quo rules. See “Contributions From Which You Benefit” in IRS Publication 526.
Note to charities: In general, ticket purchasers and others who give $75 or more are required to be told in writing the value of the benefits they receive. See IRS Publication 1771.