Centrelink will resume posting controversial debt recovery letters to thousands of Australians, as Human Services Minister Alan Tudge has defended efforts to recoup incorrect welfare payments and denied the agency made fundamental errors.

Standard procedures saw a halt to initial letters being sent to welfare recipients on December 3 last year, but thousands of Australians have reported receiving debt demands over the Christmas and New Year period, including some for tens of thousands of dollars.

Days after returning from leave, Mr Tudge said Centrelink's systems were working "as intended" and indicated only the most minor of changes were anticipated by the government.

He dismissed calls from Labor and independent MPs for the system to be shut down because of the ongoing controversy and denied an investigation launched this week by the Commonwealth Ombudsman was an indication anything was wrong.