Handing over the accounts without breaking the product

Some transfers break things and some don't, and the difference is whether the receiving side can accept the thing before the sending side gives it up.

Domains go first and slowest. A registrar transfer has a mandatory waiting period, and DNS changes propagate on their own schedule. Starting here means the clock runs while everything else proceeds in parallel.

Payment processing is the one that produces real damage if mistimed. Moving a payment account without first confirming the new entity can accept charges means failed renewals, and failed renewals mean involuntary churn the buyer inherits and the seller gets blamed for. Confirm acceptance before switching, not after.

Code and infrastructure are the easiest technically and the most commonly bungled administratively: check for personal accounts holding organisation resources, API keys hard-coded in a deploy script, and a CI system authenticating as a departing individual.

Customer communication comes last, and it comes from both parties. A support inbox that goes quiet during handover generates churn no checklist item can recover.