Products affected by the changes, which were introduced on Monday, included two-year and five-year fixed rate deals.
Andy Fell, director of brand mortgages for the companies, said: "In these uncertain times, we are committed to helping borrowers who are looking for either their first mortgage or a new competitive deal.
"We are giving practical support by providing lower rates on all our fixed and tracker mortgages and at the same time, we still have discounts on arrangement fees of £100."
At the end of last month, NatWest launched a new fee-free re-mortgage step down tracker deal.
The three-year product, which features a decreasing rate of interest, includes a facility that allows consumers to switch to a different fixed rate product after three months.
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