Cool, yeah remarkably similar to my approach.
Though using paydays to identify the last three months is much slicker than what I do. Definitely going to steal that method. The way I do it breaks around new year because it doesn’t cater for the fact that sometimes the previous month is last year…
Here’s a snapshot of what I’m doing;
One thing it looks like you might be missing is tracking overall pot balance in addition to the account balance. If you’re curious, I do this with more helper columns that look like this;
There’s more info and my template here;