HMRC savings interest estimation

SiliconChip

Does anyone know how HMRC estimates the amount of savings interest that will be earned in the next tax year? They finally finished totalling my interest for 2024/5 in January (approx. £8100) and this month they have calculated what they believe my interest for 2025/6 will be (approx £7000). Although I've still got a few more interest payments to be made before April 5th it looks to me like their estimate is pretty accurate, and I wondered how they do that.

They don't know (or maybe they do?) that I've moved another £20K into ISAs at the start of the tax year, or that I've moved money between providers to chase best rates, and they won't have received any data from banks and building societies for the current year yet, so how are they able to be so accurate? Is it possible that in fact they are receiving data earlier than we are led to believe it's submitted?

SiliconChip

https://forums.moneysavingexpert.com/discussion/comment/81889845#Comment_81889845

You're probably right, although once the tax year ends I'll be interested to see how their estimate does compare with my own final total.I suppose if it is close that's a good thing as it should mean that the tax codes they're giving me for next year will do the job they're supposed to, unlike this year where I've had to make a payment of over £1K in addition to what was collected through coding.