(1) The unauthorised or deviated development or constructions shall be considered in its entirely for its classification as "Individual Residential Buildings", "Individual Buildings other than Residential", "Flats" and "Huts and Tiled Roof Structures".
(a) Where the unauthorised or deviated development or construction of building is not in conformity with the respective rules, regularisation fee shall be levied for the unauthorised or deviated plot or floor areas which are not in conformity with the respective rules made under the respective Acts;
(b) In cases of deviated developments, or constructions already approved, part of the existing development or construction in accordance with the permission shall not be liable for levy of regularisation fee.
(c) When any development or construction is made without prior approval or in excess of earlier approval, but the whole development or construction is in conformity with the respective rules, in such case only 50 per cent of the regularisation fee over and above other charges normally leviable at current rates, are leviable and collectable as regularisation fee under these rules.
https://www.manupatrafast.com/pers/viewdoctoc.aspx?sPath=Bare%20Acts%20and%20Rules/State/tamil%20nadu/Rules/tamil%20nadu/tamil%20nadu%20town%20and%20country%20planning%20act%201971/tanamucoresatundedecoburul2002/TaNaMuCoReSatUnDeDeCoBuRul2002.htm&col=8Vmp9ozFMb/2ISz1SdixCIRVngsjs/j1lxFukHhUlVjtLjdB0bd4mmFTJWUx/aBSKBdGFQIME6VoesAFaCGBewHrWR8ddcNQuL7JwN7hYU7qHizMrFQj4LFUvb7Bkchar(43)6o706GyNkh4BCUcuVcjmbGhejF08ykNubEvKW4zqo890cktJ88vxBo32cc1YJmu9Dc/5IUlIm3BdNjSABchar(43)2R9TRHZChuWg9X1a6Zdqtl8E2/Y=#r1f1