It follows a consultation on the closure of around half of the outlets and the integration of the remainder.
Nationwide, which rescued the Dunfermline from collapse in 2009, said six of the Dunfermline outlets would close. A further 16 will integrate with nearby Nationwide branches.
But it stressed that former Dunfermline customers would now have 47 Nationwide branches, 15 more than the old society's network.
It said: "Nationwide aims to retain as many employees as possible, with redeployment to other branches in the network or Caledonia House (Dunfermline)."
There is as yet no formal redundancy process.
Branches to close are Castle Douglas, Cowdenbeath, Johnstone, Largs, Rosyth and Tranent. In Cupar, Hamilton and Dunfermline itself the Nationwide branch will switch to the Dunfermline location. In 16 other towns the Dunfermline business will transfer to a Nationwide outlet within a quarter of a mile. The society said in May it would phase the integration of the three distressed societies it acquired after the financial crash.
Tony Prestedge, chief operating officer at Nationwide, said: "We have made considerable improvements to our range of products and services, and are now in a position to ensure our members under the Dunfermline brand can have full access to the benefits our other members already enjoy."