Interlinked fire alarms that are required by law were not installed in the last Scottish Government building until six months after the deadline had passed.
A freedom of information request from the Scottish Conservatives showed that despite the deadline of February 1, fire safety laws were breached until the final alarms were installed on August 18.
The new legislation requires all homes to have linked alarms in living rooms, as well as spaces such as hallways and landings.
In the run-up to the deadline, opposition parties requested a delay in order to ensure homeowners could carry out the necessary work.
However, the Scottish Government said that the alarms could be installed within a "reasonable period" after the February 1 date.
The Tories have now slammed the Scottish Government's "shameful admission".
The party's housing spokesman, Miles Briggs, said: "This is a shameful admission from the SNP Government, who refused to move the deadline for installing these new alarms even when it became apparent that they had failed to properly inform the public of the change in the law.
"Everybody agreed that these new alarms should be installed for safety reasons but the Government didn't do enough to tell people what they needed to do.
"Now we have learned that the SNP were breaking their own law for more than six months, long after their buildings should have been up to standard.
"The SNP must now take full responsibility for their failures, and explain to the public why it took so long for these buildings to comply with the law."
A Scottish Government spokesperson said: "The Scottish Government estate consists of workplaces and a small amount of living accommodation. All buildings are compliant with all relevant fire prevention and detection regulations."
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