Scenario 1: Assume you spend $325 per month on your Forward card only on 5% categories. Further assume you spend $1,300 per month on your blue cash card, split evenly between EveryDay Purchases (supermarkets, gas stations and drug stores) and All Other purchases.

Based on these assumptions, it will take you 5 full months to hit the $6,500 spend range on your blue cash card, thus you begin earning the “big rewards” on your Everyday Purchases starting in month 6.

If you do the math out, as I did, you will see that you would earn $528 in rewards per year under this set of assumptions.

Now, if we assume that you stop using your Citi Forward card, and shift that $325 per month spend onto your blue cash card, what you find out is that you reach the $6,500 threshold one month earlier. Furthermore, these shifted balances accrue only to your “Other Spend” rewards on blue cash.

When you do the math under this scenario, despite the fact that you are reaching the $6,500 spend threshold 1 month earlier, you still would only earn $403 for the year, a 24% decline in earnings.

Perhaps the decision could be different under the unusual scenario where, right after you reach your $6,500 threshold, your spend on supermarkets, drug stores and/or gasoline rockets up substantially from where it was previously–making it much more valuable to reach that threshold more quickly. For example, if your spend on “everyday” categories rocketed to $3,700 per month in month 4 (from $650 in previous months), and stayed at that level for the remainder of the year, then the cards would generate equal amounts of rewards. If spend rocketed higher than that, you’d actually be better off with Blue Cash. But that is a serious edge case:)

thanks for all the great articles.