Stirling Council had planned to attract funding of £190,000 in "sponsorship from national companies" to help pay for this weekend's event, which clashes with the nearby 700th anniversary commemorations of the Battle of Bannockburn.
However, with just days to go before Armed Forces Day, only around £60,000 of commercial sponsorship has been secured, leaving the Scottish Government and the Ministry of Defence (MoD) to top up the local authority's contribution.
Steven Paterson, deputy leader of the SNP group on Stirling Council, said: "The Conservative-Labour administration set a totally unrealistic £190,000 target for corporate sponsorship when making the case for Stirling hosting National Armed Forces Day, and the failure to achieve even half leaves the taxpayer to fund this shortfall."
Stirling Council made the fundraising pledge in February after it emerged that the estimated price of staging Armed Forces Day had soared by a third to £524,000. The local authority, which has committed £250,000 to the event, yesterday claimed it was "delighted" to have exceeded a £190,000 target of raising cash from "sponsorship and other funding sources".
However, the projected budget for the event produced just four months ago stated that the £190,000 would come exclusively from corporate sponsorship. A further £25,000 was due to be paid by the MoD but the budget made no mention of Scottish Government money going towards the event.
New details, however, reveal that the MoD and Scottish Government will each now pay £80,000.
Mark Ruskell, Green councillor for Stirling, said last night: "It's crystal clear that commercial sponsors were not given nearly enough lead-in time to contribute funding following the announcement of Stirling's bid to host the event last year."