What cash-in changes
A cash-in refinance uses your money to reduce the new loan amount. It can lower the new payment and loan-to-value ratio, but it also ties up cash. It is not a purchase down payment and does not guarantee a rate or eligibility.
Illustration: if a lower rate alone misses a $500 payment-reduction goal, paying extra principal may reach it. Compare that cash use with keeping reserves, paying principal on the existing loan, and lender requirements.