Let's consider the simplest kind of black hole, which is one with no rotation or electric charge. The quick answer to the question is "yes, the mass is entirely within the Schwarzschild radius", but I would like to elaborate a little to explain what we are saying.

In the case of a more ordinary astronomical object, such as a planet or a star, one can have both the object itself and other things in orbit around it. The same is true for a black hole: there can be other things in orbit around it. So then the question arises, how in practice do we distinguish which mass belongs to the black hole, and which mass belongs to other things in orbit? This question is easy to answer for stable orbits, where the orbiting material is well outside the Schwarzschild radius. But when material is not in a stable orbit it may move towards the event horizon (at the Schwarzschild radius) and, in a time which will depend a lot on which observer is considered, it will pass the event horizon. After that the infalling mass soon reaches the singularity. We do not know the details of what transpires in the close vicinity of the central singularity, but the large scale picture is that the mass of the black hole has then grown a little, which we can tell my measuring the orbits of anything else still in orbit, or by gravitational lensing or other methods.

The horizon of a black hole is quite a subtle place because it is not just that the force of gravity gets to be very strong, it is more a case of the direction of time itself being "steered" in the inwards direction, so that once having passed the horizon, any object falling in cannot come out again just as surely as it cannot travel back to last week while going forward in time. This special feature applies to the horizon, and it means that right at the horizon there is a sort of cut-off: nothing can possibly hold an object fixed there. The object has to be either outside, or falling in and then it must keep on falling just as it cannot help moving forward in time.

Let's consider the simplest kind of black hole, which is one with no rotation or electric charge. The quick answer to the question is "yes, the mass is entirely within the Schwarzschild radius", but I would like to elaborate a little to explain what we are saying.

In the case of a more ordinary astronomical object, such as a planet or a star, one can have both the object itself and other things in orbit around it. The same is true for a black hole: there can be other things in orbit around it. So then the question arises, how in practice do we distinguish which mass belongs to the black hole, and which mass belongs to other things in orbit? This question is easy to answer for stable orbits, where the orbiting material is well outside the Schwarzschild radius. But when material is not in a stable orbit it may move towards the event horizon (at the Schwarzschild radius) and, in a time which will depend a lot on which observer is considered, it will pass the event horizon. After that the infalling mass soon reaches the singularity. We do not know the details of what transpires in the close vicinity of the central singularity, but the large scale picture is that the mass of the black hole has then grown a little, which we can tell by measuring the orbits of anything else still in orbit, or by gravitational lensing or other methods.

The horizon of a black hole is quite a subtle place because it is not just that the force of gravity gets to be very strong, it is more a case of the direction of time itself being "steered" in the inwards direction, so that once having passed the horizon, any object falling in cannot come out again just as surely as it cannot travel back to last week while going forward in time. This special feature applies to the horizon, and it means that right at the horizon there is a sort of cut-off: nothing can possibly hold an object fixed there. The object has to be either outside, or falling in and then it must keep on falling just as it cannot help moving forward in time.