Surely if I do the work then I am entitled to be paid for it, under the CIF standard form of building subcontract for public works?  Not so.  I hear this all the time from subcontractors. Its a mistake made by many subcontractors. That same mistake is rarely made by contractors - their teams of QS's wait in the long grass in  a final account squabble to clarify that under the terms of subcontract incorrect or no notice given for extras or variations claims dis-entitles the subcontractor to be paid for the work. That sounds harsh and it is harsh, but it is fair. Its fair when you have read the contract and more importantly understand it.  Ignorance of the law is no defence, even in conciliation, mediation, arbitration or adjudication.  So  this is a synopsis of clause 10 of the CIF standard form of subcontract for public works.  

If there is any entitlement to price 'adjustment' of the original contract sum agreed then the subcontractor must notify the contractor in writing within 10 days of the extra or variation arising referring to clause 10 (a)(1) of the contract then give further details in following 20 days.  Now you know how to get paid.