Skandia will switch to its unbundled platform pricing model on Tuesday 18 December - two weeks before the Retail Distribution Review (RDR) deadline.
Advisers will be unable to access the platform on the weekend of 15 and 16 December and on Monday 17 December.
The deadline for placing new business onto the current bundled model is Wednesday 12 December, though it will still be available for top-up under adviser charging.
Skandia has begun writing to those affected, along with further dates for scheduled maintenance on the platform.
Revealed in August, Skandia's charging structure will operate a tiered system.
The first £25,000 of assets will be charged at 50bps, £25,000 to £100,000 at 35bps, £100,000 to £500,000 at 30bps £500,000 to £1m at 25bps, with assets over £1m at 15bps.
The news follows an investor conference earlier this week that showed the platform made a loss of 5bps on every pound placed on the platform.
As of 30 June, assets under administration stood at £20.4bn, meaning a loss of £5.1m in H1.
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