If the side-job you are being offered is not an employer/employee relationship then you will have to register as self-employed but if you are jointly taxed with your husband then you are jointly submitting tax returns anyway. (If you are not jointly taxed then you should be while he's not earning).
i would be providing individual consultancy services to directly to clients and it would not be an employer/employee relationship - So based on your advice i should register as a sole trader - My husband and I are not jointly assessed as far as i know however every year when he hands in his annual accounts - the accountant takes my P-60 and we claim the tax back.... Is this the same?
On a side-note, I assume your pay would take you above the meanstest limits for your husband to get any welfare payment? He would not need to close down his business to qualify. If you have any children then FIS might be an option.
I didnt realise that he wouldnt have to deregister. the accountant advised him that he would not be eligible....