Launching on Wednesday, Investor Essentials is half the price of the site’s most popular plan which currently costs £9.99.

It comes as Interactive Investor aims to “shake things up” in launching the “entry-level” plan to cater for those who can invest up to £30,000.

One of the boons and criticisms of its subscription-based model is that it becomes cheaper for larger holdings, but is less competitive based on price for those with a more modest amount to invest.

Meanwhile, a percentage-based investment platform is generally cheaper for those with smaller amounts at the start of their investment journey.

But the new plan will offer investors the same full range of investment choice, with free regular investing, as well as the same trading fees (£5.99) for funds, investment trusts and UK/US shares as those on its core price plan.

It allows for both a stocks and shares ISA and a trading account within a single subscription, and includes educational content, model portfolios and a ‘quick start range’ for beginner investors.

It doesn’t allow free monthly trades, and doesn’t come with free Junior ISAs or SIPPs. It also needs to be set up to pay fees by direct debit and be set up for electronic communications.

Once customers reach the £30,000 threshold, they’ll automatically switch to the £9.99 investor price plan. The fixed fee stays the same whether they have just over £30,000 or over £1m.

How does it compare to rival platforms?

The annual charges were compared against competitor investment platforms by consultancy The Lang Cat.

Based on an ISA portfolio made up of 50% shares and 50% funds, and assuming two ad hoc fund trades a year; regular investing into one fund a month, and one share or investment trust per month, the Investor Essentials plan was found to be the cheapest for those with up to £30,000 to invest.

The table below shows the fees:

Richard Wilson, chief executive at Interactive Investor, said: “Investor Essentials is a pivotal moment. No longer do you need to reach for the calculator to work out at which point in time fixed fees become an obvious cost-saving choice for your investments. II now takes care of that with a simple, transparent service to meet a range of needs and budgets – and the added benefit of free regular investing.”