I came across this article I wrote a few years ago, while working as a Reward consultant and before taking up news photography. It struck me, with some force how much of this applies to photography earnings. Photos I took years ago suddenly sell, frequent requests for “free” photographs on the nebulous (the word of the month) promise of work tomorrow or a favour at some later date. Photos taken today may pay out a reasonable amount tomorrow (improbable) or a little next month or year: and so on. And, I still end up trying to explain both to HMRC and my wife, why my earnings never quite keep pace with my expenses......
http://www.hrreview.co.uk/analysis/analysis-reward/ian-davidson-dear-tax-inspector/49067