Splitit..... does not charge any late fees... If the customer does not pay splitit the installment on time, splitit withdraws the installment from the customers credit card to pay, and the debt is passed to the bank. That is why there is 0 risk for splitit, 0 risk for the merchant.
Once the debt is passed to the customers credit card..... it is up to the customers credit card as to what the fees / interest are, some may have a 30 day interest free period, some will charge 18% or whatever interest straight away. The bank gets people increasing their credit card debt that have failed to pay off a monthly installment, you might say they are likely to do it again and again, and so the bank rakes in the cash.
Splitit put hold on credit card ----> customer pays monthly debt-----> splitit reduces the hold bu the payment------> cusomter fails to pay a monthly installment-------> splitit withdraws that installment from the credit card and reduces the hold for the next month.
genius!
So technically - splitit don't charge any fees or interest........ and your bank may or may not depending on the card