No. An undrawn HELOC with a zero balance carries no payment, so it doesn't count against your DTI. Under Fannie Mae guidelines (B3-6-05), a HELOC payment goes into your ratios based on the outstanding balance. A line with nothing drawn generates no payment and isn't counted just for being open. The 5% figure you're thinking of applies only to revolving accounts that carry a balance with no stated minimum payment on the credit report. FHA and VA treat undrawn lines the same way. The picture changes the moment you actually intend to use the line. If you plan to draw against that HELOC, for example to fund part of the down payment on the new purchase, the lender needs the HELOC agreement to calculate the resulting payment and include it in your qualifying ratios. The balance you're about to create is what gets counted. Guideline treatment of revolving and HELOC accounts does vary by loan program and can be updated, so confirm the current rules for your specific loan. Mention the zero-balance line to your loan team so it's documented correctly, but it shouldn't work against your qualification.