You should never wait until after tax day (April 18th, 2017) to pay your tax.
If you know that you will owe more tax, you can compute the amended return and send a payment without sending the amended return.
The reasons it is suggested you wait are that it is quite possible that the IRS will correct the original return, and having 2 returns in the system at the same time can cause chaos.
According to the IRS:
“The IRS may correct mathematical or clerical errors on a return and may
accept returns without certain required forms or schedules. In these instances,
there's no need to amend your return. However, do file an amended return if
there's a change in your filing status, income, deductions, or credits...
Don’t file more than one original return for the same year, even if you haven’t received your refund or haven’t heard from the IRS since you filed. Filing more than one original return for the same year, or sending in more than one copy of the same return (unless we ask you to do so), could delay your refund....
RS offers several payment options. You can pay online or by phone, mobile device, cash (maximum $1,000 per day and per transaction), check, or money order. Go to www.irs.gov/payments for payment options.
Pay online. IRS offers an electronic payment option that’s right for you. Paying online is convenient and secure and helps make sure we get your payments on time. To pay your taxes online or for more information, go to
www.irs.gov/payments. You can pay using any of the following methods.
IRS Direct Pay. For online transfers directly from your checking or savings account at no cost to you, go to www.irs.gov/payments.
Pay by Card. To pay by debit or credit card, go to www.irs.gov/payments. A convenience fee is charged by these service providers.
IRS2Go. You can access Direct Pay or Pay By Card by downloading IRS2Go, the mobile application of the IRS.
Pay by phone. Paying by phone is another safe and secure method of paying electronically. Use one of the following methods:“
It is wise to wait until the original return has processed, but you do need to make the tax payment on time to avoid penalties and interest.
