Already SE but starting additional business - tax/NI implications?

oompahloompah

HI everyone
I am currently SE in a business partnership, and as such self assess my share of the business profits each year, and pay class 2 NI contributions monthly.
However, like many around the country, business has been very slow recently and I have been thinking about doing other SE work on my own (i.e. without the other business partners). I have discussed the business implications with them and they are all supportive, I would still be contributing my share of the effort required to keep the original business going.
However, I was wondering what happens from a tax point of view? I imagine I don't need to inform HMRC of this change as I will still be SE and still in the business partnership? Providing I declare the additional SE income on my tax return am I right that this would be okay?
Also, I think that new businesses can have their first financial year lasting as long as 15 months, would this apply in this case or would I need to declare everything I earned between now and April on the upcoming tax return?
And I imagine I don't need to pay additional Class 2 national insurance contributions, but can someone tell me if this is all correct?
Thanks!

chrismac1

You'll need to fill in a second set of self-employment section of the tax return. Strictly you'll need to declare anything between now and 5 April 11 on your 10-11 return. This can work to your advantage if you have setup costs but little income - this produces a loss which will reduce your overall tax bill. Once the business makes profits you'll pay 9% (from 6 April) Class 4 NI on the combined profits of the 2 businesses - between 7,225 and 42,475 which are the new levels for 11-12.