Equifax credit score discrepancy in 1 month, why?

Question

I just went to Citi Bank's website (which gives free FICO scores from Equifax for users of some credit cards) and I realized that the score I saw there was a whopping ~50 points higher than the number I saw on Mint.com, despite the fact that they both claim to have received the number from Equifax.
The only difference is the fact that Mint checked my score at the end of February 2015, whereas Citi checked it at the end of January 2015.

However, nothing unusual has happened to my credit history in between these two. I can confirm on Mint's credit report that nothing seems wrong, so I'm quite confused:

1. What can cause such a discrepancy?

2. Whom should I contact to understand what is going on -- Mint, Citi, Equifax, or other?
   How should I contact them -- file a dispute, call them, or go somewhere in person?

Note that I don't feel I'm "disputing" anything, since I don't know if there is any cause for a dispute, and hence I'm not sure it makes sense to open a dispute with Equifax. I just want to know what is going on and why two third-party agencies claim to have received such wildly different numbers from the same agencies in the span of 1 month.

Answer 1

The free credit score from Mint.com is not a FICO score. Citi does give us Equifax FICO score but even with FICO there exist so many variations. Fair Isaac has developed around 50 different scores using different formulas - only very few are actually accessible to consumers. Most free credit scores are simply FAKO scores (which are never used by lenders). They can choose to put more weight on some element of your credit report; or ignore your history as an authorized user (which is a common credit rebuilding technique). It is just pointless to directly compare credit scores from different sources, because that tells you nothing other than that they are different.

Now there are still ways to utilize those free scores. You can try collect them periodically and watch the trend of each score. The idea is that, FAKO or FICO, the factors that affect your score are very similar. If you see your Mint.com score going up two months straight, chances are that the actual FICO scores that lenders use would also go up. I was able to verify this with my CreditKarma, CreditSesame and Transunion FICO scores.

Answer 2

It is common for credit scores to change on a daily basis. In the span of one month, there can be a lot of changes to your account that can change your score by 50 points. Without knowing the actual details of your account, I can only guess. The simplest explanation would be your debt to credit ratio. If you recently made payments without increasing your total debt, that is one simple explanation. The other way to decrease your debt to credit ratio is to apply for and get approved for a new credit card. That increases your credit score just by the simple fact that you have more credit available thus lowering your ratio. There are other contributing factors but nothing that would raise your score by 50 points.

Answer 3

At this point in time, monitoring the actual credit number reported on your credit reports is counterproductive. This is because there are many algorithms of scores that you get to see, the criteria those algorithms look for also change, and the score any particular lender is using may be different. It also isn't always clear which score you are seeing or using.

You need only to keep track of things adversely affecting your credit report and improve those things, as these are what potential lenders will judge you on, more so than whatever arbitrary scoring mechanism they happen to be using. This will make you more credit worthy and give you access to lower interest rates and banks will also try to woo you with more perks to get your business. But the score alone can have massive (100+ point) divergences between your credit history and other different scoring metrics, as such month to month fluctuations are just white noise in your credit eligibility or perceived ability to pay.