The direct to consumer platform said all any new investment transfers higher than this amount that hit before 1 April 2014 would not pay a custody or platform fee until October.
The group has also suggested it would waive any exit charges of any new client who was dissatisfied with its service and wanted to leave within the first year.
Taking this decision should encourage aggregation of assets from various tax wrappers, with the transfers possible across a mix of funds, shares, investment trusts and cash.
With an annual platform fee on funds of 0.25 per cent, Charles Stanley Direct said the potential saving could be at least £625. Shares and investment trusts have a custody fee of 0.25 per cent a year (which would normally be capped at £150).
Head of Charles Stanley Direct Rob Hudson said: "Many clients have expressed an interest in using our service, but some have been put off by high transfer fees from competitors. Our six month fee free offer helps offset the cost of moving. In addition, we will guarantee that if any client isn't satisfied with our service and wishes to transfer to another provider in the first year, we will waive any exit charges."
Hudson said the recent flurry of platform providers offering their post-RDR share class charging structures has highlighted the complexity for investors, warning that headline offers might be subject to small print that reduced their appeal.
"The recent pricing announcements from many competitors are welcome, although in our view many have been dithering and are long overdue. Investors finally have clarity on charges, although comparing like for like still isn't easy. Differences in what platforms offer will be a key differentiator and it still seems strange that many don't offer clients the choice of shares and investment trusts alongside funds," he added.
Beyond this offer, Charles Stanley Direct will charge 0.15 per cent for a balance transfer of £500,000 of more, so a client with £1m would pay 0.25 per cent on the first £500,000 and 0.15 per cent on the second £500,000, giving an average annual fee of 0.2 per cent.
