Technically you have to report and pay capital gains if the change in value is more than $200. In your case 15% gain is probably not more than $200 so you woul

Technically you have to report and pay capital gains if the change in value is more than $200. In your case 15% gain is probably not more than $200 so you wouldn't have to report it. However if you're talking about $100,000 initial FX transaction you would have to report the $15,000 as a long or short term capital gain.