Limited company v salaried staff

[beeko]

I am currently in a contract role and paid, via an agent, into my private limited company. IR35 legislation will probably deem that from April 2020, I should be treated as an employee. As part of a consultation process, the company with whom I do the work (not the agent) is proposing to make all contracted workers (who are willing to do so - those unwilling will be shown the door, I reckon) permanent. I have yet to know what their offer (salary wise) will be, and may not yet know for a few weeks yet.
Are there any formulas for comparing earnings as a staff member versus earnings as a limited contractor?
I know various factors such as pension contributions, holiday pay, Employer National Insurance contributions, etc, have to be taken in account.

[robbob]

Generally its probably 20-30% higher rates being self employed - i guess the main difference between the two being that you get 12% extra if you were previously only billing for 46.4 weeks worked if you took bog standard holidays and rate only reflected actual hours worked.

1000 week employee 52k
100 week worked self employed - take of your 5.6 weeks holiday that £46,400

Pension probably depends on what company gives you as a freebie and there is likely other less important items like perks sick pay maternity pay - company car etc

I would say though if you run company very tax efficiently at present and scoop of some input vat as profit and claim allowable expenses - computers / mobiles / travel 45p mile / use of home / annual function - the employed route will likely see material increase in tax due all other things being equa.

Worse case your rate drops 30% and you are paying more tax too

[beeko]

Thanks, robbob. Very helpful

[beeko]

Right, so it turns out that the salary on offer is a lot better than I was expecting. Not quite what I hoped for but pleasantly surprised that my potential new employer has given all of its contractors decent enough offers.

They are proposing we go from being contractors to permanent staff members from 1st March 2020. Do I need to issue myself a P45 as a (self-assessed) contractor? Do I need to inform HMRC beforehand or immediately upon going PAYE of my change of circumstances?

Thanks all, in advance.
Happy Christmas to you all and all the best for 2020.