Using sumif and offset together

I am currently using "sumif" to add up numbers in columns based on if there is a certain word in each row. My formula is =SUMIF(A5:A1820,"Special",L5:L1820).

I would like to be able to use this formula across all columns in the worksheet (from, L onwards), but autofill does not seem work properly for this, as A5:A1820 gets changed to a different column. I cannot get the offset function set up correctly. Does anyone know how I can set up the formula?

Thanks for any help.

You can autofill the formula if you use $ signs to "fix" the relevant column references: Try

=SUMIF($A5:$A1820,"Special",L5:L1820)

Thanks again daddylonglegs!