How early Immigration health Surcharge can be paid?

Dear board members

Iam going to apply for my wife’s visa on FLRM in August 2018.

I have heard that the immigration health Surcharge is going to be doubled this year so to avoid extra surcharge I have paid the immigration health Surcharge today and got the IHS number, I put this number on my online appointment for premium service but did not get the required date so I did not finished my application yet.

My question is that how early IHS Surcharge I can pay.

If I booked my appointment for August and by July immigration health Surcharge is increases does that apply to my application as well although the appointment is booked before the increased or does it apply to those who get IHS Number after increase?????

There is no guideline that how early the IHS can be paid but it should be paid as part of application. If you have paid IHS now but apply later when IHS will have been increased then more likely you will be asked to pay remaining balance.