There is a question as to the exact location as to where the evil angels presently reside. Some Bible students believe that all of them are bound in the dark realms of the unseen world, while others think that some angels remain unbound, and live in the heavenly realms.
VIEW 1 ALL ANGELS ARE BOUND IN DARKNESS
The Bible tells us that angels have been bound.
And the angels who did not keep their own position, but left their proper dwelling, he has kept in eternal chains in deepest darkness for the judgment of the great Day (Jude 6).
The evil angels are said to live in darkness, bound until the day of judgment.
Tartarus
The Bible speaks of them being bound in a place called "tartarus."
For if God did not spare the angels when they sinned, but cast them into tartarus and committed them to chains of deepest darkness to be kept until the judgment (2 Peter 2:4).
This place is the lowest level of judgment - the place where the worst offenders go.
Abyss
The place of darkness is also called the abyss.
[the demons] begged Him [Jesus] not to order them to go back into the abyss (Luke 8:31).
From these passages, it is argued, that all angels have been bound. There is no hint that some angels remain loose or may live in some other place. The "sinning angels" are all bound, waiting for judgment. Yet they do have some access to humanity to cause various problems.
VIEW 2 SOME ANGELS REMAIN UNBOUND
Another view argues that the angels who have been bound do not constitute all the angels. It is argued that some evil angels remain free to cause chaos on the earth. If these evil angels are causing chaos on the earth, as everyone agrees they are, then the question may be asked, "In what sense are they bound?" Obviously they have a very long chain!
Heavenly Realm
One of the reasons people believe that some evil angels remain unbound is Paul's statement in Ephesians.
For our struggle is not against enemies of blood and flesh, but against the rulers, against the authorities, against the cosmic powers of this present darkness, against the spiritual forces of evil in the heavenly places (Ephesians 6:12).
He said our battle is against various orders of evil spiritual powers in the unseen, heavenly, realm. This seems to indicate these are beings who roam about freely - they are not the ones that are chained.
Loosed During The Great Tribulation
Before Christ returns to the earth, certain of these bound angels will be loosed for a short period of time.
So the four angels were released, who had been held ready for the hour, the day, the month, and the year, to kill a third of humanity. The number of the troops of cavalry was two hundred million; I heard their number (Revelation 9:15,16).
Until that time, these angels remain bound.
Fight With Michael
Certain angels will make war with Michael and his angelic army in the heavenly realm.
And there was war in heaven, Michael and his angels waging war with the dragon. And the dragon and his angels waged war (Revelation 12:7).
Summary
The Bible makes it clear that evil angels have been bound in darkness because of their rebellion against God. The question is whether this constitutes all the evil angels, or merely a portion of them. All sides agree that evil angels still cause problems on the earth. To say, however, that all angels are bound, yet they still cause untold problems on the earth, makes the idea of their being bound a bit meaningless. If they can still roam around the world and cause havoc, they are not really bound in any real sense of the word.