Tory MP Christopher Davies had admitted submitting two false expenses invoices.
His lawyer Thomas Forster QC said Davies accepts his responsibility and expresses his "sincere and unreserved apology" for what he described as a "disastrous accounting episode".
However District Judge John Zani said although there was no financial gain for Davies, he committed "two very serious offences" which were "absolutely intended to deceive".
The first charge was providing false or misleading information for allowances claims contrary to section 10 of the Parliamentary Standards Act 2009.
He admitted that in March 2016 he made a claim under the MPs' allowances scheme and provided an invoice he knew to be "false or misleading".
The second charge was attempting to provide false or misleading information for an allowance claim using an invoice "that he knew to be false or misleading" in April 2016.
The court heard how the two charges relate to around the time when he was setting up his constituency office following the 2015 snap general election.
He had contacted a photographer in his constituency and purchased nine images from him to decorate and display in his constituency office, using his own money to pay the £700 for them initially.
There were two budgets available to him, the Start Up Costs Budget - for office furniture and IT equipment - and the Office Costs Budget, both of which he could claim the full amount from.
But Philip Stott, prosecuting, revealed Mr Davies found in February 2016 that only £476.02 was left in the Start Up Costs Budget, with £8,303.75 remaining in the other.
He then proceeded to create two fake invoices, so the £700 cost could be split between the two budgets - £450 to the Start Up and £250 for the other.
The court heard he could have claimed the full amount from the budget with the larger amount available, or had the photographer create new legitimate invoices to split the cost that way.
Davies highlighted in a letter to the Party Investigating Officer sent in February 2018, in which he responded to the allegations against him, that he had been "told in a conversation by a more experienced MP that you could 'split' expenses'' and therefore attempted to do so.
Davies has since repaid the £450, with the £250 claim never submitted.
The case has been referred to the Crown Court for sentencing.