When a homeowner tells a mortgage servicer that it has made an error, federal rules set two clocks. Within five business days, the servicer must send “a written response acknowledging receipt of the notice of error.”
The full answer can take longer. For most errors the servicer has 30 business days, and it may extend that by 15 business days only if it tells the borrower in writing, with reasons, before the 30 days run out.