I have started working part time as a DJ, how do I go about declaring this as I am a PAYE worker in my day job

if they have recodnized your talent then go for it and sign a contract for paye

You will need to fill in a TR1 to register for self-assessed tax, so say you register for self-assessed in 2008, you will declare this income in 2009. At the beginning of the new tax year (January) you will receive a Form 11 in which you will have to declare your self-assessed income and your PAYE income. You can also claim your tax credits in this form and deduct any expenses you made to do your DJ job. You then submit the completed Form 11 to the Tax Office before October 31st the same year.

Do you mean declaring it as in taxes? If you get paid at your DJ job, you just add up your two jobs together and you pay taxes on both jobs.

If the people that pay you at the DJ job pay you in cash and don't have your Social Security number, the IRS doesn't know that you've made that income.

If you see yourself being a full time DJ, you should look into getting a business license. This will save you money in the end. You can claim different losses so you don't have to pay taxes if you have a small business license. You can be a corporation, be an independent contractor, or self-employed.

If you're really worried about it, you can put aside 33% of each paycheck from the DJ job, that's what you do usually if the company that you work for doesn't deduct income tax each paycheck, otherwise you'll end up paying.