RBS announced its move to rebrand RBS IP to NatWest Intermediary Solutions last month.
It meant that subsidiary broker brands RBS, First Active, and the One Account stopped operating as of the end of January.
Previously each brand represented a certain type of mortgage: RBS was for purchases and home movers, First Active handled remortgage business, the One Account dealt with current account mortgages, and NatWest predominantly managed buy-to-let cases, though some mortgages were distributed through Countrywide under the NatWest brand.
It has now emerged that the rebrand will have a knock-on effect.
With effect from February 12 existing customers with RBS, First Active, and the One Account still within the deal period who want to port their mortgage will have to go to RBS direct.
For example, this means that borrowers who took out a two-year fixed rate deal with First Active a year ago and now want to move house will have to go direct to keep their existing deal.
Brokers wanting to submit pipeline house move applications for the affected brands will have to do so by February 12.
Borrowers who have already reverted to the SVR, or who are willing to pay early repayment charges, can still arrange to port their mortgage through brokers.
NatWest borrowers are unaffected by the changes.
As part of the rebrand the repeat proc fee paid to brokers on First Active remortgage cases without additional borrowing will come to an end on March 31.
A spokesman for NatWest Intermediary Solutions says that brokers were notified of the changes for existing customers on January 28.
He says that the rebrand will ultimately lead to a more streamlined application process and that it will make it easier for brokers to place new mortgage deals under the one NatWest brand.