Consultancy work after redundancy

About six weeks ago I was made redundant by my employer. I received a redundancy payment that was in excess of £30k. An opportunity has now arisen for me to undertake some consultancy for the same employer which would most likely begin towards the end of this calendar year. I would be working for my previous employer as a self-employed consultant registered for self-assessment. I have been advised that there is no employment law issue with me working for my previous employer as a consultant. However, I have also been informally advised that if I work as a self-employed consultant for the employer who made me redundant, I would then have to pay income tax and national insurance contributions on the £30k portion of my redundancy payment that was previously exempt from those deductions. Can anyone confirm if this is, indeed, the case? If so, how long does this situation apply for? Am I never able to work for my previous employer as a consulant without losing that exemption? Many thanks for any advice.

Hi,
If your former employer choses to engage you as a consultant as a sole trader, then that has nothing to do with your redundancy payment.  
You are a sole trader and invoice the company for your services.  
Please register for self-assessment as a sole trader and report your gross turnover / expenses and pay tax through a self-assessment tax return
Please see Become a sole trader: Register as a sole trader.
Thank you