The lender did not formally announce the cut but appears to have made the change when introducing its new calculator for self-employed cases earlier this week.
Broker illustrations shown to Mortgage Solutions from the calculator which have since been replicated, indicate the lender will now only offer a maximum of 4.25 times income to self-employed borrowers.
This is a reduction from the five times income that was previously available.
It does not appear that the LTI cap for employed borrowers has been changed.
The lender did not dispute the changes when contacted by Mortgage Solutions.
A NatWest spokesperson said: “We continually review our proposition to ensure it is in line with current market conditions.”