The maps and schedules held by the commissioners passed to the [[Inland Revenue]] (the predecessors of [[HMRC]]) and are now held in [[The National Archives]] at [[Kew]]<ref>Foot, p.20</ref> (classes IR29 and IR30). MostIn ofa thepartnership extantwith parishThe copiesNational areArchives<ref>{{cite nowweb|title=The heldNational atArchives theresearch county record officeguide|url=http://www.nationalarchives.gov.uk/help-with-your-research/research-guides/tithes/|website=The diocesanNational copiesArchives|accessdate=7 forAugust most2017}}</ref> Welshand parishesa arefamily heldhistory in thedata website,[[National Library of WalesTheGenealogist]], atit [[Aberystwyth]].is Priorpossible to the publication of large scale [[Ordnance Survey]] maps inview the lateapportionments 19th century,and tithe maps wereon frequentlyTheGenealogist's copiedwebsite.<ref>{{cite (inweb|title=Tithe wholerecord orsearch part)on for other purposesTheGenealogist|url=https://www.thegenealogist.co.uk/tithe/|website=TheGenealogist|accessdate=7 forAugust example2017}}</ref> inThe connectionblack withand plannedwhite railways,maps orand asapportionments partthat ofare theonline titlecover deedsall transferredthat onare aavailable salefor of land. More recently, tithe mapsEngland and apportionmentsWales havewhile oftenthere beenis usedan forongoing referenceproject by genealogistsTheGenealogist andto other historical researchers. For many parishes they providescan the onlyoriginals largein scalecolour, mapsome showingof thewhich landscapethey priorhave toalready the [[Industrial Revolution]],<ref>Harley,made pavailable.35</ref>{{cite andweb|title=TNA theyresearch frequentlyguide provide- theHow earliestdo evidenceI search for thetithe [[fieldmaps?|url=http://www.nationalarchives.gov.uk/help-with-your-research/research-guides/tithes/#7-tithe-maps-ir-30|website=The system]]National inArchives|accessdate=7 theAugust 2017}}</ref> parish.
Most of the extant parish copies are now held at the county record office. The diocesan copies for most Welsh parishes are held in the [[National Library of Wales]] at [[Aberystwyth]]. Prior to the publication of large scale [[Ordnance Survey]] maps in the late 19th century, tithe maps were frequently copied (in whole or part) for other purposes: for example in connection with planned railways, or as part of the title deeds transferred on a sale of land. More recently, tithe maps and apportionments have often been used for reference by genealogists and other historical researchers. For many parishes they provide the only large scale map showing the landscape prior to the [[Industrial Revolution]],<ref>Harley, p.35</ref> and they frequently provide the earliest evidence for the [[field system]] in the parish.
