Tax/NI on second job

[redmapleleaves1]

I'm a single mum of young adults. I work full-time, compressed hours 5 days in 4 in one job, and for the last 18 months I've been doing contract work another day a week elsewhere to try to pay off the mortgage/uni maintenance/the gas bill. The time for the first tax return is coming. The umbrella organisation for the second job has been subtracting tax and NI at source, but now I'm wondering:

*in the past I've been self employed. Would there be any benefit to reactivating my sole trader company for this second job retroactively?

As I'm already paying full time NI from the first job, can I get these back from the second? What about the additional class 4 NI if I did it as self employed, would I still need to pay these, or is it only if you are just* self-employed?

*In the second job I'm driving 70 miles to and from it each day I work. It would be great if I could claim mileage and then pay tax on the remaining income. Is this possible if I am self employed for this contract? Basically I am contracted by umbrella organisation, have worked for two organisations in this second job, but the second one has been since Feb and likely to continue to next summer.

Thanks if you've read this far. I know I probably need to speak to an accountant or similar, but want to try to get my head round the options with the power of MN first.

Read this:

www.gov.uk/defer-national-insurance

to see whether you would be able to defer your class 1 NI on your second job - then the correct bill taking into account both jobs would be collected at the end of the year if any more was owing.

you may be able to apply for a refund:

www.gov.uk/claim-national-insurance-refund

Class 4 is payable on any self employment once you reach the threshold, regardless of whether you have an employment or not.

Self employed vs employed is quite complicated, and may not be up to you to choose - I would have a word with your employer first about whether they think it would be possible.

Thanks so much @travellingfamily, really grateful. My takeaway, apart from the specific links, is that it is all much more complicated than I'd blithely assumed. Really helpful.