I only had to pay a one off payment security bond but surely, if and when the amount of capital held reduces to the point that the bond no longer matches it, the bond will be reduced at the next due date. If it isn't, I would write to them and point this out.
I can't see why the OPG would charge for this.
I looked into this for Scotland, so it may not be the same in England and Wales. We pay an annual caution premium (security bond) with regard to my mum's Guardianship. The level of bond was set by the court in 2014. The company that manages the bond are not legally allowed to reduce the sum protected, even though my mum's estate has reduced. I was told we would have to go back to court to have an order issued to the cautioner for the level of bond to be reduced.
So, that's a long way of saying you need to ask the COP. The security bond provider should be able send you a schedule of premium charges against a rising scale of estate value. You will then see how much saving you could make by reducing the annual fee. In our case it was only about £250 and our solicitor said it would cost much more for him to apply to the Sheriff Court for a hearing in chambers to obtain the order. In England there may be a different procedure. Also, in our case, the Guardianship is only awarded for 3 years, so if my mum lasts that long our Guardianship will need to be re-applied for in 2017 anyway.
I never did understand why I had to pay the bond via a one-off payment when I first became my husband's deputy as most seem to have to pay it annually. So you may well be right about the payment as if wouldn't have affected me.
However, once my husband's capital reduced to below the amount where the annual supervision fee was necessary - the OPG method of charging for this changed during my deputyship - it was up to me to let the know this fact despite it being obvious from the previous year's annual report.
"I never did understand why I had to pay the bond via a one-off payment when I first became my husband's deputy as most seem to have to pay it annually. "
My understanding is that it is up to the Court, ie Judge, to decide and that annual payments are usually asked for larger estates. Life expectancy would also be a sensible factor but I don't think this is taken into account.
Went looking and on a bond provider's site found:-
QUESTION 3: How Often Do I Need To Pay The Bond Premium?
The premium is normally payable annually. We will write to you before each anniversary to request payment. On small estates it is possible to arrange a Surety Bond with a single payment for the lifetime of the Bond.