Solicitors' Undertakings: The Promise That Moves the Money
12 February 2026 · Mary Molloy Solicitors
On completion day, a lender transfers a six-figure sum to a solicitor before the old mortgage is released and before the new one is registered. The instrument that makes this possible is the solicitor's undertaking — one of the most consequential documents in conveyancing and one of the least understood by clients.
What the undertaking promises
In a remortgage, the core undertaking to the new lender is threefold: to use the advance to redeem the existing mortgage, to ensure the new mortgage ranks as a first legal charge, and to register it and lodge the certified title. To the old lender, the accountable trust receipt undertakes to hold the deeds in trust and return them or redeem the loan.
Why banks accept a letter instead of waiting
An undertaking is a professional obligation, enforceable through the courts and through the solicitor's regulator, and treated by the profession as close to inviolable. That enforcement architecture — not sentiment — is why institutions advance funds against it. Without undertakings, every remortgage would need old and new lenders to complete simultaneously in a single room, and the market as it exists could not function.
What it means for how your file is run
Because an undertaking cannot quietly be unwound once given, solicitors are exacting about the conditions being right before completion: redemption figures fresh, insurance in place, title certified without unresolved qualifications. If your solicitor declines to complete until an item is fixed, that is the undertaking's discipline protecting everyone in the chain — including you.
Read more in our main guide: The Remortgage Process in Ireland, Step by Step · or back to the blog.
This page contains general information about Irish law and practice. It is not legal advice, it may not reflect your circumstances, and reading it does not create a solicitor–client relationship with Mary Molloy Solicitors. We do not advise on taxation; please speak to your accountant or Revenue. In contentious business, a solicitor may not calculate fees or other charges as a percentage or proportion of any award or settlement.