Rule Of 78 Interest
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It's a method some lenders use to allocate interest more heavily to the earlier months of a loan than a standard amortization schedule would, meaning that paying off the loan early can result in less interest savings than expected under a Rule of 78 loan.

It comes from the sum of the digits one through twelve, representing the twelve months of a one-year loan; each month's interest share is weighted based on its position, with the first month carrying the largest share of that sum.

Under simple interest amortization, interest is charged only on the remaining balance each month, but under Rule of 78, a disproportionate share of total interest is front-loaded regardless of the actual declining balance, which disadvantages borrowers who pay off early.

Its use has been restricted or banned for longer-term loans in many jurisdictions due to its unfavorable treatment of early payoff, though it may still appear on some short-term consumer loans, so it's worth checking your loan's specific terms.

Check your loan agreement's terms directly, or compare the interest charged in the first few months against what a standard amortization schedule would show for the same principal, rate, and term — a noticeably higher early interest charge suggests Rule of 78.