I'm pretty good on declarations to Revenue, in fact squeaky clean. I had a large capital loss two years ago which I declared, and have been carrying forward. I'll have another one this year. I can see why Revenue wouldn't be sticklers for evidence when I'm handing over money for capital gains, but what about a loss? We're talking high six figures. They didn't ask me for any evidence at the time, but what about if I start writing off gains against it? What might they ask for in future? I'd prefer to be forearmed and not trying to chase share account statements years down the road when the accounts might no longer exist.