Photography, like any other art form, becomes art at the hands of the artist and in the eyes of the viewer. It doesn't matter if it's digital or analog. The type of camera or equipment used will not make it Art. Art is the expression or application of human creative skill and imagination, producing works to be appreciated primarily for their beauty or emotional power.
Nowadays, the photographic community tries to make the distinction between manipulated and unmanipulated imagery, so as to define a line between "digital art" and the digital artist, but the means, to the end, is just a tool. If one says a camera is a recording device and thus records just what it sees, they clearly have no concept of what it takes to make a camera and the programming behind the look each company is using to differentiate themselves from the next.
Some photo contests differentiate their types of photographic art this way:
- Photojournalism: Unposed, undirected, limited post-processed images.
- Composite: An image that is made up more than one capture to create the final print.
PPA makes no such distinctions in their rules. So if it's printed and you made the original exposure and it's the right size, you're good to go.
AIPP is the same as PPA in that they don't distinguish the differences.
Neither of the distinctions above change the artistic impact of an image. That comes from the photographer. How they chose to record it, what equipment they liked or had on them, and how they made their creative decisions.
When your talking to the tax people, you take their rules and see what fits. When it comes to photography though, all great photographers are artists, and recognized as such by the art community. How they do their taxes is probably a very different matter entirely.