Civil Service McCloud RSS for those receiving their pension

pinnks

Has anyone reverse-engineered the Option 2 summary on their Civil Service RSS?  As expected, mine suggests I am better off staying with my Premium benefits, however, out of interest I am trying to reconcile the amounts shown in Option 2.  Option 1 is my current Premium position and fine (of course) and Option 2 would be moving to Alpha from 1 April 2015 to 16 April 2019.

I can reconcile the Option 2 pension and lump sum amounts but not the survivor pension and overpayment position.

My understanding is that the survivor pension is 37.5% of the uncommuted pension under both Alpha and Premium.  Option 1 (current position) Premium survivor amount is a simple 37.5%, but if I take 37.5% of the gross Option 2 pension (shown on the RSS lump sum options page, which matches my calculation too) I don’t get the survivor pension shown Option 2.  I get an amount that lower than Option 1, reflecting the reduced gross pension under Option 2, as I would expect. The difference is about £650 per year on a £20k survivor pension!

Am I missing something in terms of how the survivor pension is calculated for the RSS?

The next issue is the overpayments.  I agree the lump sum overpayment but cannot reconcile the pension overpayment. 

If I take my actual pension amounts for the part years 2019/20 (from 16 April) and 2024/25 (to January), and full years in between, then calculate the Option 2 position for those 6 year, I get an overpayment of ~£2,625 compared to ~£2,075 on the RSS.  I won’t be opting to change but I would like to understand the maths. 

 Anyone got any thoughts?