employed 60 per cent but will also be earning as freelance

[scripsi]

next tax year it seems that i am going to be 60 per cent employed (earning 18,000 gross) and then also I shall be earning approximately 8,000 gross from "freelancing" for clients of my employers on a couple of projects - they have taken advice and believe this is all above board (they just don't want to fully employ me it seems).
So, tax wise, I am not self-employed. How would I declare this to the tax authorities and how can I calculate the extra in tax I would be paying?
Also this will probably be happening only for the one year (as these are very specific freelance projects) and I wouldn't want it to affect my tax code. How should I go about all this?

Tax-wise, you WILL be self-employed.

You will in fact be both employed and self-employed, as you'll have an income from each source. So you'll need to register as self-employed with hmrc and compete a tax return each year. Your employment tax should continue to be paid through paye, but you'll need to put some of your self-employed income aside to pay the tax you owe on that.

thanks Rally, I am going to be in touch with HMRC. If I can find a 100 per cent position in the meantime then I will quit this one as I am essentially being pressured into being partly self-employed.

Apologies for the simplistic question, but is it right that you have to complete a self-assessment tax form at the end of the January following the tax year, so for example for 2014-2015 you would complete the tax form in January 2016? Or would it be January 2015, with me trying to guess how much I would earn until April?

If you start self-employment in 2014/15 then you need to submit the first tax return by 31 January 2016. It can be submitted any time between April 2015 and end of January 2016, you don't have to wait till January to submit.

thanks Riksti, that makes more sense!