You'll need to apply at least 3 weeks before you make a payment.
You can't apply online if you need a reference number for a trust.
If HMRC needs to contact you about anything confidential they'll reply by phone or post.
Follow the instructions on paying your Inheritance Tax bill by cheque.
You must use the Inheritance Tax reference number (not the online estate report reference number) to make a payment, and allow at least 3 working days for it to reach HMRC.