What's a Meter Serial Number (MSN) and why does it matter?

A Meter Serial Number (MSN) - also known as a meter ID sometimes - is a unique string of letters and numbers assigned to a specific water, gas or electricity meter. You can find the MSN stamped, engraved, or printed near the barcode on the front of the meter, or listed on your energy bill under headings like “Meter Readings”.

Why it matters:

• Helps your new supplier locate the correct meter during a switch, especially important in properties with non-standard or overlapping addresses and also new build properties that may have the address listed differently on the national database compared to the Royal Mail.

• Ensures accurate billing by confirming usage from the right meter.

• The MSN changes when the physical meter is replaced - unlike fixed supply codes like MPAN (electric line into the property) and MPRN (gas line into the property) making it a vital identifier.

Finding your MSN:

• On the meter itself - look near the barcode or display panel.

• On your energy bill - check the “Meter Readings” or “Meter Details” section (may be labelled “Meter Number,” “Meter ID,” or “MSN”).

What if you can’t find it?

• Your new supplier will try to proceed using the supply address, but giving them the MSN upfront speeds the process up and ensures accuracy.

• If the MSN is unavailable or mismatched, your supplier may need to follow up, or in rare cases, may be unable to complete the switch.