Acknowledge the reason
Respond kindly, whether it is budget, timing or a change of plan.
Confirm what stops
Say which work pauses and what is already in progress.
Settle outstanding invoices
Bill for work done so far before pausing.
Set a pause window
Agree a restart date or a review point.
Explain how restarting works
Say how soon you can resume and whether the schedule or price may change.
Put it in writing
Send a short summary the client can confirm.