HR - notice period advice

[Movelikewater]

My notice period is one month. I gave written notice yesterday 11.08.22 - my manager says my last day is 12.09.22. I think I should finish on 10.09.22 and my actual last day be 09.09.22.

Additionally I have taken two days over my annual leave entitlement to this point of the year. Can I offer to work these two days (12 and 13 September) to avoid losing pay? Or do I need to come back from my leave early?

Well if your work policy isn't explicit about whether the month's notice is inclusive or exclusive of the day you give notice it will come down to interpretation, there isn't a legal definition AFAIK, I would actually say your last day is the 11th Sep myself which being a Sunday means your actual last day is the 9th (and even if I was of your manager's view, I would waive the requirement to work the Monday personally as makes little sense to make someone work a random Monday, much tidier to finish at the end of the week). However if they're adamant is it really worth arguing the toss over one day?

Re the annual leave, so you are essentially offering to work two extra days 'unpaid' in lieu of the extra annual leave taken? I guess there's no reason why not although at my place what we'd do is extend your leaving date, pay you as normal for those two days and then still deduct the two days you owed us which 'net' would be the same effect but if that would be your preference then you can only ask?