So how much as a childminder do you charge for Ad hoc care

[anewyear]

Just been reading another thread, and it got me thinking,

I Only childmind 4 children, all after schoolers, I could have my full quota of 6 if i wanted but I dont, as I also have 2 children of my own (8 & 12yrs)

However every now and then I do a bit of ad hoc childminding and I charge my hourly rate £4 PH, I charge extra for snacks (the hourly rate for CM's in the village are between £3.50 - 5.50 so Im told)
Ive not increased my fees at all in the 3 years Ive been minding.

So anyhow on another thread, it implied that some people charge more for Ad Hoc care, if I was to do this, Ive no idea as to how much more to charge?
Gratefull for any thoughts on this.

I charge my normal rate, but I do increase my rates each year.

I charge by the day, flat fee of £40, or if its before/after school it's £5 per hour. HSMM how much do you increase by each year if you don't mind me asking?

I charge my normal rate.

I charge £6ph for ad hoc or part time. The previous cms of my 2 after schoolies charged £10 ph for ad hoc or part time.