basically 9 years are cached and the last year is recalculated as needed. you have a source of truth for what the data looked like at moment T+9 years, you can

basically 9 years are cached and the last year is recalculated as needed. you have a source of truth for what the data looked like at moment T+9 years, you can just take as granted. and then process the transactions following that date "live" as needed