A bstract Limits are set on the pair production of scalar leptoquarks, where all possible decays of the leptoquark into a quark ( t , b ) and a lepton ( τ , ν ) of the third generation are considered. The limits are presented as a function of the leptoquark mass and the branching ratio into charged leptons for up-type (LQ 3 u → tν / bτ ) and down-type (LQ 3 d → bν / tτ ) leptoquarks. Many results are reinterpretations of previously published ATLAS searches. In all cases, LHC proton-proton collision data at a centre-of-mass energy of $$ \sqrt{s} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> = 13 TeV recorded by the ATLAS detector in 2015 and 2016 are used, corresponding to an integrated luminosity of 36.1 fb −1 . Masses below 800 GeV are excluded for both LQ 3 u and LQ 3 d independently of the branching ratio, with masses below about 1 TeV being excluded for the limiting cases of branching ratios equal to zero or unity.