(1) The unauthorised or deviated development shall be considered in its entirety for its classification as per Development Control Rules such as ordinary building, special building or multi-storeyed.
(a) Where the unauthorised or deviated development is not in conformity with Development Control Rules, regularisation fee shall be levied for the unauthorised or deviated plot or floor areas which are not in conformity with Development Control Rules as prescribed in rule 6.
(b) In cases of deviated developments, already approved part of the existing development shall not be liable for levy of regularisation fee, only if it is substantially relatable to the earlier approved plan geometrically in shape, size and in usage including number of dwellings. If not relatable, that portion shall also be treated as unauthorised, and regularisation fee assessed accordingly.
(2) When any development or construction is made without prior approval or in excess of earlier approval, but the whole development is in conformity with the Development Control Rules, in such case, only development charges and other charges normally leviable at current rates are leviable and collectable. In that case, any previous fees or charges remitted shall be duly adjusted or substracted, on proof of remittance.
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/apascolrefechmearrul1999/ApAsColReFeChMeArRul1999.htm&col=8Vmp9ozFMb/2ISz1SdixCIRVngsjs/j1lxFukHhUlVjtLjdB0bd4mmFTJWUx/aBSKBdGFQIME6VoesAFaCGBewHrWR8ddcNQuL7JwN7hYU7qHizMrFQj4LFUvb7Bkchar(43)6o706GyNkh4BCUcuVcjmbGhejF08ykNubEvKW4zqo890cktJ88vxBo32cc1YJmu9Dc/5IUlIm3BdNjSABchar(43)2R9TRHZChuWg9X1a6Zdqtl8E2/Y=#ch1f3