How to declare "other income"

[vector]

I'm a PAYE employee of a limited company earning say 25000

I also happen to also make about EUR 3000 selling services myself
I issue paper invoices

How do I actually inform the revenue about the 3000?
what form do I use, or do I write them a letter

the facts
I pay my suppliers 2000
I make a profit of 1000
I want the revenue this and they will then tell me how much of the 1000 they want and I pay them

 

[Tenacious]

Use this form. It called Form 12.

[broken link removed]

 

[vector]

yes, excellent thanks for the link