The IRS already knows you have made payments for the 2018 taxes owed. If you still have a balance after making those payments then you can pay the balance with the 2018 tax return that is being filed. And if filed and paid on or before April 15, 2019 there will not be a failure to pay penalty.
You are Not "required" to pay what is shown on your tax return for the taxes owed when filing the tax return.
