When gifting our grown kids, if my wife and I exceed the annual limit of $15,000 will we be actually taxed or does the amount over just go against the lifetime limit?

Let's say we gave one grown kid $25,000 more in one year than allowed, $15,000. If I file the IRS 709 do I actually get taxed or does the excess just go against the lifetime limit? I am wondering if I really get taxed if I exceed the $15,000 limit?