signature is signed for the contract vs signature is signed on the contract

Some examples from the web:

• Performance of the contract shall not start before the contract is signed.
• Performance of the contract may not start before the contract is signed.
• 3. The award notice shall be sent when the contract is signed.
• When the contract is signed and delivered.
• In both cases the contract under which experts are to be hired is signed with a consulting firm.
• By derogation from Article 156(2), the contracting authority shall release the tender guarantee when the contract is signed.
• The award notice shall be sent when the contract is signed.
• It shall be released when the contract is signed.
• The contract is signed and she will be here any minute.
• Apparently there are problems with regard to the legality of the contracts signed for carrying out the work to enlarge the harbour of El Musel in Gijón.
• Creating the impression that the consumer cannot leave the premises until the contract is signed or the payment made.
• Creating the impression that the consumer cannot leave the premises until the contract is signed or the payment made.
• The duration of the contract is 25 years, provided that a seat agreement is signed with the French Government.
• Once the contract is signed, we pay you and we want you to laugh or cry on demand.
• The contracting authority may, before the contract is signed, either abandon the procurement or cancel the award procedure without the candidates or tenderers being entitled to claim any compensation.
• Such information should be provided before the contract is signed and should give the unsuccessful candidates and tenderers the reasons why their application or tender has been rejected.
• The Agency may, before the contract is signed, either abandon the procurement or cancel the award procedure without the candidates or tenderers being entitled to claim any compensation.
• The contracting authority may, before the contract is signed, either abandon the procurement or cancel the award procedure without the candidates or tenderers being entitled to claim any compensation.
• As long as the contract is signed before the baby is born, it's all good.
• The ECB may cancel a tender procedure at any time before the contract is signed without the candidates or tenderers being entitled to claim any compensation.

Some examples from the web:

• Performance of the contract shall not start before the contract is signed.
• Performance of the contract may not start before the contract is signed.
• After more than 3 years of combat, the armistice that ended the Korean War is signed on July 24th.
• The contracts were signed on 30 January 2009.
• An amendment to the contract was signed on 9 July 2002.
• The contracts for that EUR 3 billion capital injection were signed on 16 November 2009.
• 3. The award notice shall be sent when the contract is signed.
• When the contract is signed and delivered.
• The Declaration is signed on behalf of the government by the Minister of Finance, who submits it to Parliament.
• The contract for this study was signed on 20 May and its budget amounts to EUR 100000.
• The third one concerns an agreement inherited through BE's 1999 acquisition of SWALEC, with TPL. The contract was originally signed on 26 June 1991.
• The contract for that EUR 1,4 billion capital injection was signed on 20 May 2010.
• The contract regarding the completion of this phase was signed on 19 January 2006, and the work is currently progressing satisfactorily.
• In both cases the contract under which experts are to be hired is signed with a consulting firm.
• By derogation from Article 156(2), the contracting authority shall release the tender guarantee when the contract is signed.
• The award notice shall be sent when the contract is signed.
• It shall be released when the contract is signed.
• The contract is signed and she will be here any minute.
• Portugal argues that the contract was signed on 14 November 2003, i.e. while the TDM Regulation was still in force, and therefore remains eligible for aid.
• Portugal states in this respect that the contract in question was signed on 14 November 2003, i.e. while the TDM Regulation was still in force, and therefore remains eligible for aid.