I work with a mate doing fencing decking and stuff. We're both registered as self employed. You'll both need to pay national insurance (about £2 a week) and declare tax on earnings at the end of the year. You can earn up to around £4500 without paying tax per year, anything over that its around £22 in every £100 that you earn (so put that aside). VAT you don't need to worry about, you just have to pay it yourself. Theres no getting stuff 'vat free' or anything - at the end of the day someone has to pay it (you). You'll need public liability insurance which is pretty cheap I think (around £200 per year). I don't think you NEED to register as a business with companies house - as long as you pay the government tax they're happy. So to start up - register as self employed and get some insurance, and start working. If you really want to go into a proper legal partnership, you will need to write up a partnership agreement, theres lots of examples on google.