Get Date of certification expiration User/machine

How to retrieve expiration date of specified certificate for user and machine.

<#
.SYNOPSIS
    This script to provide user/machine date of expiration for specified cert in certificate store 
.DESCRIPTION
    This script to provide user/machine date of expiration for specified cert in certificate store 
.PARAMETER -issuer
    use -issuer parameter to include your certificate name

.EXAMPLE
    get-certExpiration -issuer "KTSubCA0*"

#>

Function get-certExpiration {

param(
    [CmdletBinding()]
    [parameter(mandatory = $true)][String]$issuer 
)

   #######################################################################3
    $user = Get-ChildItem -r "Cert:\CurrentUser\my" | Where-Object {$_.Issuer -match $issuer } | select subject, issuer, @{n='ExpireInDays';e={($_.notafter)}}
    $machine = Get-ChildItem -r "Cert:\LocalMachine\my" | Where-Object {$_.Issuer -match $issuer } | select subject, issuer, @{n='ExpireInDays';e={($_.notafter)}}


    $report = $user, $machine
    $report


    ######################################
    #### you can save and export data to CSV file  
    #$user | Export-Csv  c:\Report-cert.csv -Append -NoTypeInformation
    #$machine |Export-Csv c:\Report-cert.csv -Append -NoTypeInformation
    
    
}