For landlords, carpet is a recurring capital cost and a recurring source of deposit disputes. Both are reduced by the same thing: documentation and planned cleaning.
This is a practical schedule around the tenancy cycle.
At check-in
Record carpet condition thoroughly with dated photographs in the inventory, noting existing marks and wear. A vague inventory is the most common reason deductions fail at adjudication.
Cleaning between tenancies and keeping the invoice establishes the standard you expect the property returned in.
During the tenancy
For longer tenancies, mid-term cleaning protects the asset and gives an opportunity to spot problems such as leaks or pet damage early.
Providing entrance matting and making clear that spills should be reported promptly both reduce end-of-tenancy surprises.
At check-out
Clean after the property is emptied and before the check-out inspection, so the clerk sees carpet in its final state and it has had time to dry.
Keep invoices and before-and-after photographs. Where a stain cannot be fully removed, a professional's written note is far stronger evidence than an assertion.