From YWAMKnowledgeBase

Don't forget to get a receipt!!!

Really - just don't do it!!!

You will need to file it and then keep it for up to 10 years (more depending on law of your country!)

Just get a receipt!

(Apparently on my Operation Year, just a few weeks in, my room mate was woken up in the middle of the night by me sitting bolt upright in bed. "Don't forget to get a receipt!", I said. Then fell back to sleep again... --Kev-The-Hasty 19:55, 1 February 2010 (UTC))