Decide the cutover strategy
Three viable approaches:
- Big-bang cutover — flip everything at once. Lowest cost, highest risk. Suitable for small books with clean data.
- New-business cutover — new loans onto new platform; legacy book stays on old. Lowest risk, longest dual-cost.
- Vintage cutover — migrate one vintage / cohort at a time. Balanced. Most common for mid-size books.
Audit your current data quality
Before any migration, audit:
- Borrower contact information completeness.
- Property record completeness (address normalization, valuation source).
- Payment history integrity (no orphaned entries, no duplicate postings).
- Escrow balance reconciliation against bank statements.
- Document storage coverage and naming consistency.
Migrating bad data into a new platform makes the new platform look bad. Clean first.
Math verification first
Before you migrate a single loan, run the new platform's servicing calculations against your existing loans for at least 90 days of history. Per-diem accrual, escrow balance, modification reset, prepayment penalty — verify they match. If they don't, you find out now, not at cutover.
Dry-run migration
A real dry-run migration produces:
- A field-by-field diff for every loan.
- A list of every record that would error or warn.
- Math reconciliation per loan (balance, accrued interest, escrow).
- A go / no-go decision artifact for your operations team to sign off.
Side-by-side reconciliation
For at least 30 days post-migration, run both platforms in parallel against the same payment events. Compare every output. Surface any divergence. By day 30, the new platform should be producing identical or expected-equivalent results.
Cutover day mechanics
Plan the day carefully:
- Customer notification 14 days prior.
- Final reconciliation T-1.
- Read-only freeze on the legacy system for 4-8 hours.
- Final sync, integrity check, smoke test.
- Activate the new platform.
- Customer notification: “you're live, here's your new portal URL.”
The first 30 days
Expect:
- Increased support volume (login, portal navigation).
- Edge-case data discoveries (the field that nobody knew was used).
- Monthly statement parity verification.
- Investor-facing communication if applicable.
With clean prep, the new platform feels like an upgrade, not a disruption. With sloppy prep, every edge case becomes a customer call. Invest in the prep.