When Does a Cash-Out Refinance Beat Taking Out a Second Mortgage?
Needing to tap home equity for a large expense usually leads to the same fork in the road: replace the entire mortgage or leave it alone and add a second loan behind it.
The short answer
A cash-out refinance replaces the entire existing mortgage with a new, larger loan and gives the difference in cash, while a second mortgage — often a HELOC or home equity loan — leaves the original mortgage untouched and adds a separate loan on top of it. Which one costs less depends heavily on how the new rate compares to the rate on the existing first mortgage, since a cash-out refinance resets the terms on the entire balance, not just the new money borrowed.
Why the existing rate matters so much
If the current mortgage carries a notably low rate, refinancing the whole thing to access equity means giving up that rate on the full balance, not just on the cash being taken out. A second mortgage, by contrast, only applies its rate to the new amount borrowed, leaving the original loan’s rate and remaining term untouched. This is often the single biggest factor in the comparison: a cash-out refinance tends to make more sense when the new blended rate is close to or better than the old one, while a second mortgage tends to hold up better when the first mortgage’s rate is well below current market rates.
Thinking in terms of a blended rate
One way to compare the two is to estimate the blended interest cost across both loans in the second-mortgage scenario, then compare that blended figure to the single rate offered on a full cash-out refinance. If the blended rate ends up higher than the refinance rate, the refinance may be the cheaper path overall, and vice versa.
Closing costs and structure
- Closing costs. A cash-out refinance typically involves closing costs similar to an original purchase mortgage, calculated on the full new loan amount, while a second mortgage’s closing costs are usually smaller since they’re based only on the new amount borrowed.
- Loan count. A cash-out refinance results in a single monthly payment, while a second mortgage means managing two separate loans, two servicers, and potentially two different rate types.
- Combined loan-to-value. Both options are limited by how much loan-to-value a lender will allow, and a HELOC used as a second lien has its combined loan-to-value calculated using the existing first mortgage balance plus the new line.
Other factors worth weighing
Beyond rate math, the two paths differ in flexibility. A HELOC used as the second lien offers a revolving line that can be drawn down and repaid over time, which suits a variable or ongoing need better than a lump-sum refinance. A cash-out refinance, by comparison, delivers one fixed amount at closing and generally locks in a new rate and term for the life of the loan, which can suit a one-time, well-defined expense more cleanly than an open-ended line.
Putting it together
There’s no single answer that applies across situations, since the right choice depends on the gap between the old and new rates, how much cash is needed, how quickly it needs to be available, and whether a revolving line or a lump sum fits the underlying need better. Running the actual numbers — the existing rate, the market rate for each option, and the closing costs involved — tends to be more useful than defaulting to whichever option is more commonly discussed.