You can't literally move a balance from one property to another, but the idea underneath the question has a real tax angle worth exploring. Pulling cash out of an equity-rich rental to pay down your primary is mostly interesting for tax reasons rather than rate reasons. The mechanism: mortgage interest on your primary residence only helps on your tax return to the extent it, plus your other itemized deductions, clears the standard deduction, and the standard deduction is fairly high (confirm the current amount for your filing status). Plenty of households with mid-size primary mortgages find the interest barely clears that bar, so much of it delivers little or no extra benefit. Interest on a loan against your rental works differently. It deducts against the rental income, directly reducing the taxable income from that property. So shifting debt off the primary and onto the investment property can put the same dollars of borrowing in a more tax-efficient place. Whether the move actually helps depends on your full tax picture, the rate you'd take on the rental cash-out, and your reserves. Model it with a CPA who knows real estate before you move any money. Nothing here guarantees a tax outcome, and this is general information, not tax advice.