I have a four day a week contract, and we operate a salary sacrifice scheme for our pension scheme, which I am part of.
I have agreed with my employer that I will work five days a week going forward, but will do so on an ad hoc basis without a change to my contract. I understand the downsides to this - my pension and holiday entitlement won't reflect the increased hours, and so on, but I don't want it to be contractual at this stage, because I know there will be quite a few weeks when I can't or don't want to work the extra days. We might review the situation in a few months time to formalise it, but for now this works for me. The deal is that I keep track of time and let her know how many extra days I have done each month, and she will pay me for those at my equivalent daily rate, based on my four day a week salary.
That's fine, but my employer (small business, she doesn't really have much idea of employment law, and nor do I) has asked if my day rate should be at my base salary, or my post salary sacrifice rate. I contribute 6%, and therefore there is quite a material difference over time. If I work 40 of the 52 possible extra days this year, it works out at about £1400.
The thing is, I don't know the answer. As these payments aren't contractual and my pension won't reflect these extra days, I'm tempted to say it should be my daily rate before salary sacrifice. But that's obviously going to cost her more, so I want to think it through properly before going to her with an answer. Any advice much appreciated.