Paying a Reduced Tax and HMRC

Are there any lawful loopholes that allow me to reduce the tax I have to pay? I’m self employed and my accountant has put expenses on my self assessment which I haven’t actually made. My accountant says they are allowable expenses (playing with very small numbers) but I don’t known if I’m doing something wrong Islamically. I’d be saving 25% on tax approximately but I’d rather not do even this if it’s wrong.

May Allah bless you.
As Muslims, we should avoid making a false declaration when filling up our tax return.
However, if there are legal loopholes that you can actually benefit from without lying, then there is nothing wrong with it.
One thing I will say is as self employed people, sometimes we can also overlook at the amount of expenses we incur, and we end up not mentioning them either. Maybe your accountant was being mindful of that.

Kind regards