Are Seperate Bank Accounts Needed???

[melntu]

My partner and i have our own company (ltd) and that hs its own seperate business account, however, the business is really new and as yet we are not taking any money in wages from the business.
I work full time and so we can easily manage, but, my partner has also been doing some other work during his "down time" from Ltd co. for this he has registered as self employed and for CIS.
My question is, when he was paid my his contractor, I simply paid the cheque into our joint account and put a portion away in a savings account for his future tax bill.
Is it OK to do this or does he need (another!) seperate account top pay his self employed income into.

Also, what do I do about NI. As he is not drawing a wage from Ltd co he is not paying any there, should he not be paying a weekly amount for the self employed bit? Should I call the inland revenue about this?

Thanks