The company has decided to lower the point at which investors pay the reduced annual commission of 0.325%.
The starting point for the lower fee bracket was previously £300,000 but has been altered to £180,000. This will take effect from April.
Clients will be charged 0.325% for investments for portfolios on the first £600,000 and 0.29% for cash. The bracket range goes from £180,000 to £600,000.
Where the portfolios are less than £180,000 the first £60,000 will be charged at 0.5% for investments and 0.45% for cash.  Previously, clients with portfolios of less than £300,000 paid 0.5% on the first £60,000 and 0.325% for the remaining £240,000.
Transact said a client with a portfolio value of £180,000 will now be paying £105 less per annum – a saving of over 15% and predicted "many thousands of existing customers" will benefit as well as new. See table below for changes.


Further changes, which have already been announced, will take effect from March.
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Buy commission will be halved to 0.05% and no charge will apply for portfolio group values over £1 million.
The Transact dealing charge (to cover brokerage for investments listed on or admitted to a Stock Exchange) will also be reduced again from 1 March.
Dealing charges for standard, phased and regular transactions will be up to a maximum of £3.75, £1.00 and £0.50 respectively.
Ian Taylor, chief executive, said: "2014 was another profitable year for Transact and funds under direction now exceed £17bn.
"We have a clear strategy and with prudent management and decision making we can pass on savings derived from our scale and specialisation in the wrap market.
"It is also very satisfying that some of the benefits of our commitment to responsible pricing will be passed on to both new and existing customers.
"We are very proud of the fact that advisers continue to choose Transact as their preferred platform."
The firm will keep listening to feedback to improve the service it provides, he added.   

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