Most owners get their lead count from one place, usually the CRM, and trust it. But the CRM is downstream of the phone system and the website, and things go missing between them. This is how to reconcile last month by hand. Thirty minutes with three exports.
They are close. The plumbing is sound. Do this quarterly.
The CRM is well below the sources. Leads are being made and then lost before they are written down. Common causes: a form integration that broke on an update, calls that nobody logs, a staff process that only records leads that turned into estimates. Each of those is a lead you paid for that the business never saw.
The CRM is well above the sources. Leads are arriving from somewhere the tracking is not watching. Referrals, a directory, a number on a truck that is not tracked. Not a problem, but it means the marketing report is taking credit for less than it should or more than it should, and you cannot tell which.
The form log and the inbox disagree. The form is sending some submissions and dropping others, or the mail is landing in spam part of the time. Run the form test. Does your form deliver
A CRM tells you what it caught. The call log and the form log tell you what happened. Compare them once and you will know how many leads a month never reached the business at all, and that number is usually the cheapest one to fix in the whole operation.