ILR never expires... it is indefinite, hence the name:
Indefinite Leave to Remain. The only way you will lose ILR is if you leave the UK to live somewhere else and do not return for more than 2 years.
It's only the physical BRP card that has an expiry date on it, meaning the card itself needs to be renewed every 10 years (like a UK driving licence does)... it doesn't affect your actual immigration status. Having said that, they are getting rid of BRP cards completely on 1st Jan 2025 anyway and moving everything online, so even if you were to renew your BRP, the new one would only be valid until 31st December 2024.
However, since you have applied for citizenship, I don't think it will be an issue - chances are, your citizenship application will be processed before mid-March anyway, as recent citizenship processing times for people here on the forum have been around 3-4 months (applied in May, approved in Sept; applied in July, approved in Oct). And once your citizenship has been granted, your ILR BRP will be cancelled and you will need to return the BRP card to UKVI.
Hello!
I applied for citizenship on 1 September (biometrics & doc scan on 20 Sept) - haven't heard anything since, but I know they can take 6+ months. My ILR expires mid-March. I wasn't going to renew it as I'm opting for citizenship, but what happens if citizenship takes more than 6 months and my work ask for updated proof that I can work? Am I not legally allowed to work/reside in the UK if my ILR expires while I'm waiting on my citizenship?
Another Q - does anyone know if they will ask for additional proof of residency if they need it or just reject outright? I sent my last 5 P60s, but now regretting not sending additional proof. Was completely thrown when they said I should be able to prove using only 5 sheets of paper!
I think you'll be fine with what you have sent. You just need to show you have been residing/working in the UK for the whole 5 years, and your 5 P60s will show that.
