The IRS usually uses Letter 4364C to inform you they have accepted your amended returns or some other aspect of an amended return. They will send you a bill if you owe. Letter 4364C is essentially the same letter as the Notices CP21 & CP22.
If you owe the IRS it is best to pay them immediately, even if you have to incur debt. The amount of penalties & interest which the IRS charges you is devastating. But, if you can't immediately pay, we'll have to stop all levies immediately.
Initially, we usually need to make a payment agreement with the IRS to prevent levies. Then, we devise a specific strategy for you to deal with this debt. In many ways, the passage of time will work in your favor. After two years from the date the returns were filed, most income taxes are dischargeable in bankruptcy. At that point, you can file bankruptcy, make an Offer-of-Compromise or simply keep making payments.