I have no debt. I have paid off 3 mortgages and own my homes free and clear. I pay my single credit card off each month and have never paid interest on unpaid balance. I have an excellent income and never have missed paying a bill yet my credit score is slowly eroding from 860 to the mid-700s. The reason I'm given is that my credit card balance is too high. I use that card for business travel and always pay the entire due balance, but my credit score keeps going down.
The most recent reduction was accompanied by the reason that the change was due to a lack of payment history! I have 50 plus years of payment history and just finished paying off a zero-interest car loan last year, so where's the lack of history? The suggestion was that I take out a loan! What a farce in suggesting the solution to solving a credit score problem is to take on debt.
This shows that the FICO score is not a valid indicator of credit worthiness and that it is prejudicial toward those who manage their finances and credit well.
I suspect you're looking at a non-FICO score because FICO tops at a max of 850, below your 860. In fact, many of the FICO versions out there don't even hit 850 and are below that on the high-low range (820s, 830s). FICO also factors in your closed accounts provided they show on your report. There are some non-FICO scores that ignore closed accounts which can also account for the trend you are seeing. I definitely would discourage getting into any debt for the sake of any credit score. It's not needed.
Most lenders out there have some sense of intelligence and will objectively look at your credit, score aside. Based on what you said, you're in great shape. Congrats!
Some FICO scores go up to 900 (Bankcard Enhanced FICO scores) and some go to 950 (FICO NextGen). They can be obtained when you apply for a CC or loan by certain banks (CITI and Chase for Bankcard and PenFed for NextGen) and either get denied or don't get the best rates. Which FICO scores each banks use may differ by location but at least from my personal experience, CITI and Chase have always used a bankcard enhanced score and PenFed has always used NextGen.