They do allow you to request a waiver due to unintended effects of tax reform as long as you paid at least 85% of your tax obligation. But if you paid at least 90%, you don't owe a penalty anyway, so it's a very narrow sweet spot to get that waiver.

Is your total federal tax obligation less than $20K? In order to owe a penalty, you have to have prepaid less than 100% of what you owed last year or 90% of what you owe this year. So in order to owe a penalty, your federal income tax has to be under $20K. (Actually, there is a new stupid rule that if you make over $150K, then 100% of last year isn't enough to escape the penalty - it has to be 110% of last year. But 90% of this year is still good.)

But even if you owe a penalty, it isn't that much - it's essentially 5% interest (assessed on a daily basis). So assuming your $2K is evenly spread out over the year (as opposed to all of your income came in January 2018 and you earned nothing the rest of the year), you're looking at less than $50.

Just pay your $2K ASAP - don't wait until April 15.