Migrating 126,000 ISA and JISA accounts in seven months for The Children’s ISA

The client

The Children’s ISA

The Children’s ISA is the UK’s specialist provider of Children’s ISA and Junior ISA (JISA) products, supporting families and young savers across the country, including thousands of young people supported through the Share Foundation charity.

The challenge

Migrating a full children’s ISA book without disruption or risk

TCI needed to migrate its entire book of ISA and Junior ISA accounts from its previous platform provider, following nine years of dependency on that platform for core services.

The scale and sensitivity of the migration made this a complex undertaking. In total, 126,000 investor accounts needed to be transferred, including associated cash and asset holdings, with no interruption to service and no detriment to investors. Many of these accounts belonged to children and young people, increasing the importance of accuracy, auditability and protection throughout the process.

TCI was also seeking a faster timeline than the industry norm. Traditional phased migrations of this scale can take well over a year to complete, extending operational risk and uncertainty for providers and investors alike.

The solution

An all-in-one migration built for speed, accuracy and investor protection

Quai Digital was appointed to deliver a full, end-to-end migration programme designed to manage complexity at scale while maintaining regulatory confidence.

Rather than adopting a phased migration approach, Quai Digital delivered an all-in-one transition. This enabled TCI to onboard to Quai Digital’s platform while simultaneously migrating all existing investor accounts and executing a bulk transfer of cash and asset holdings.

Key elements of the delivery approach included:

• Parallel platform onboarding and account migration to shorten overall timelines
• Embedded reconciliation and compliance checks at every stage
• Bulk handling of cash and asset transfers
• Close, daily collaboration between Quai Digital and TCI teams
• Rapid resolution of operational challenges, including inactive accounts, duplicate direct debits, bulk contribution uploads and data inconsistencies

Quai Digital’s API-driven platform also supported an iterative rollout of new features during the migration, easing operational pressure while maintaining continuity of service for investors.

The results

126,000 accounts migrated in half the industry average time

The migration was completed in record time.

From contract signing in January 2025, all 126,000 investor accounts were successfully migrated by August 2025. The full programme took seven months end to end, around half the typical industry timeframe for migrations of this size.

Once engagement began, the core migration programme itself ran for five months. The physical migration of investor account data and the bulk transfer of cash and assets were completed in just four weeks.

Throughout the programme, investor protection and service continuity were maintained, with no disruption to end clients.

With TCI now live on Quai Digital’s platform, the business has a modern, scalable foundation designed to support long-term growth, enhanced automation and improved customer journeys.

Why it matters

Setting a new benchmark for complex, regulated migrations

Large-scale migrations only succeed when clients have complete confidence that investor protection is embedded at every stage of delivery.

By combining operational and regulatory expertise with specialist platform technology, Quai Digital has demonstrated its ability to deliver complex migrations reliably at scale — preserving continuity of service while enabling long-term modernisation.