Simon Lovell, former head of music at Colne community school, Brightlingsea, Essex, had been told not have anything to do with funding for school trips but handled payments anyway.
The GTC, sitting in Birmingham this week, said headteachers and the public were entitled to expect teachers to be honest and that Mr Lovell had breached that standard.
It gave Mr Lovell a conditional registration order and excluded him from financial dealings for the next three years.
Dorothy Elliot, chair of the conduct committee, said: "I cannot be satisfied that he would not act inappropriately in the future."
She said the deception was not for personal gain and that the school could have given Mr Lovell, who suffered extreme anxiety and had personal and medical problems, more support.
The GTC heard that Mr Lovell accepted cash and cheques to the value of Pounds 860 as part of a payment for a school trip to Lake Garda, Italy. In doing so he breached a warning from Terry Creissen, Colne principal, that he was to have nothing to do with the financial aspect of school trips.
The warning was issued after Mr Lovell was found to have misled the school over the financial arrangements for a trip he organised to the United States in July, 2002. The GTC hearing was told that parents alerted Mr Creissen to Mr Lovell's financial involvement in the Lake Garda trip after they enquired about a receipt for a payment he issued incorrectly.
Mr Creissen said: "Mr Lovell told me that all monies for the trip had been passed to a departmental colleague. When asked if he had received a cheque that morning he said he had not."
Mr Lovell conceded at the hearing that he had not told the truth to Mr Creissen. "I did not tell a lie, but I did not tell all the facts," he said. "Some of the cheques were in my possession for several weeks before I handed them on. I misrepresented myself to Mr Creissen."
Mr Lovell said that in the weeks running up to the meeting in December 2003 his judgement had been impaired by personal and medical difficulties. He suffered from extreme anxiety and had been prescribed antidepressants, which his doctor confirmed could have affected his concentration.
Mr Lovell said: "I tried to keep my personal life out of my work, but it was affecting me in school, even though I didn't realise that fact until much later."
Philip Winfield, a music teacher, told the head that Mr Lowell had entered his classroom moments before the meeting, presented him with a handful of cheques, and asked him to say he had had them all the time.
But Mr Lovell denied he asked Mr Winfield to lie on his behalf, claiming that he panicked. "Had I been given adequate warning of the meeting I doubt whether I would have acted the way I did."