You can get a tattoo over it but here are a few things to keep in mind.
[U]Infection and healing.
Your incision needs to be completely healed before you try to get a tattoo over it. 18 months should be sufficient, but your doctor can tell you more easily. Skin heals at different rates, no two people are the same. It would be a bad idea to go in without knowing for sure to avoid the risk of infection in that area.
having another c-section later
If you DO get a tattoo over the scar, be aware that should you need another c-section later on they will have to cut over the tattoo and scar, it probably won't be too pretty.
tattoo artist and artwork
Some tattoo artists won't do work over scaring. A lot of the time the texture of the skin is different and it effects the overall look of the tattoo. Make sure you find an artist who has a lot of experience in this area, and who will work with your scar to give you the best bang for your buck on your body.
Look for an artist who is willing to go over your skin with you and take the time to draw up something unique, and be willing to change the design a bit mid-tattoo if necessary. Yet another reason to find someone with a lot of experience. Sometimes you have to make minor adjustments in order to get the best look.
This would be especially important for you because you said you have a portion of your skin that has raised scarring. Ink holds differently on different parts of the epidermis. So if you are wanting a solid ink, single color, tattoo the blue or black may look a bit lighter or darker on the parts of skin that have no scar. Your artist may suggest putting a bit of color in the tattoo so that it is a bit less uniform, because your skin isn't all uniform in that area.
It may be possible that in time this raised bit of scar will go down. The very best advice is the advice of your doctor about your skin, ask them what they think the next time you go in.
Hope this helps!
