Non-filer
A non-filer is a person not on the Active Taxpayers List, who therefore pays substantially higher withholding tax on banking, vehicles, dividends and property.
The higher rates are deliberate. On a property purchase a non-filer can pay several times the filer rate of advance tax, which on a large transaction exceeds the cost of a decade of filing.
Related terms
Filer
A filer is a person whose name appears on the Active Taxpayers List, meaning they filed their income tax return for the relevant year on time.
ATL
The ATL is the FBR's weekly published list of taxpayers who have filed their return on time, and being on it is what qualifies you for the lower withholding tax rates.
Section 236K
Section 236K is the advance income tax collected from the buyer when a property transfer is registered in Pakistan.