Self-study fifth A-level???

I'm currently studying maths, further maths, computer science and economics in year 1 at an accelerated rate. I find my subject choice fairly easy with 4 A*s predicted. I wanted to A- A-level accounting (AQA) as I'm interested in finance and figured that it would be impressive to future employers & unis. Is what I'm suggesting logical and or worth it?

No don't do that. 4 is plenty and won't impress anyone.

How much of the A level course have you covered so far?

No, I'm trying to learn all of the economics first and roughly 60 ish % through the syllabus which is much more than my classmates. Im doing this so i can try do a full econ paper to see if self studying an a level is feasible and take what i learnt to accounting as that is an a level with a low amount of content but mostly exam technique which i excel at.

It's not a good idea - how much maths have you covered?

~70% regular maths, 35 ish% further

So that's not accelerated then.

I would stick with the 4 - it's far too early to predict A* in your subjects, especially FMaths!

Thats about a full a level in 5 months.. ???