Prepayment Penalty

[GGun]

I paid $4,812 in Federal tax in 2018.  I've prepay-ed $8,822 so far for 2019.  My approximate total tax will be about $10,709, so a balance due in April will be $1,887+-.

Am I penalty free or do I need to pay any additional prepay-ed taxes before April?

If I do, by what date is it Due?

[DanielV01]

You should be penalty-free.  Even though you owe more than $1,000, you avoid the penalty if you have paid in at least 100% of your 2018 tax liability.  If you are in the "high income" category, you would need to pay 110% of the 2018 liability to be penalty-free.  If your total 2018 liability was $4812, then the $8822 you've paid in will meet the requirements and avoid the penalty, provided that you paid your estimates (or had withholdings) timely.