We have some money in a Northern Rock account; when the First Active eSaver was announced I was interested to see how splitting your money between three of the better deposit providers would affect the overall return after say 10 years, versus just leaving it all in Northern Rock. I did out a little spreadsheet, viewable here: [broken link removed]
I factored in DIRT by reducing the CAR by 23% (for example, I figure that the Northern Rock rate is 1.03465 after DIRT). & I assumed the rates are fixed over the ten years (quite unlikely?).
With an initial amount of 50k I think you'd make an extra 2.4% or so---over the 10 years. If you had 30k total at the start, you'd come out with an extra 4%. With 100k to start with, you'd get an extra 1.2%.
Obviously, the less money overall, the greater the proportion earning higher interest (assuming 15k First Active + 10k Rabo), so the greater the advantage in splitting the money over the three providers.
I have no financial training since Junior Cert business studies. Bear that in mind if these figures are of interest!
Are there any other advantages to splitting across the three providers, beyond the potential increase in return?
Also, am I right in thinking that 2.4% over ten years translates to (10th root of 2.4) = .24% extra in the effective interest rate?