This is the single most common mistake we see when borrowers come in asking for cash-out refinance. They have a 3.0–4.5% first-mortgage rate locked in from 2020–2021, and a loan officer has pitched them on cash-out refi to access equity for a renovation or debt consolidation.
Doing the cash-out refi means giving up that 3.5% rate forever and replacing it with today's market rate (~6.5%). On a $400K loan, that's about $700/month more in P&I. Even after netting out the cash they receive, the borrower is paying tens of thousands more over the loan life.
The correct answer in this scenario is almost always HELOC or home equity loan as a second lien. The second-lien rate is higher than the first-mortgage rate (8–10% vs 3.5%), but you're only paying that higher rate on the borrowed portion — not on your entire loan balance. The math:
Cash-out refi: $700/mo extra on $400K (whole balance)
vs.
HELOC at 9%: $750/mo on $100K cash (the borrowed portion only)
Even though the HELOC's per-dollar rate is higher, the absolute dollar cost is lower because you're not re-pricing the full $400K balance. Protect the rate, layer on the equity product.
This calculus inverts when your first-mortgage rate is already at or above current rates. If you have a 7.25% first lien and current rates are 6.0%, then refinancing the whole balance does save money — and adding cash-out becomes the natural choice if you also need equity. Run both scenarios. The math is unambiguous once you do.