Off-budget spending, where the cost of activities deemed to have special characteristics is not included in the official budget, is widely used across the world.
In Poland, it was initially deployed for spending to weather the pandemic but now encompasses a surge in military and other expenditures.
"Budget funds are becoming less and less transparent," Supreme Audit Office President Marian Banas told Reuters.
Importantly, they note that the off-budget spending still gets captured under European accounting rules.
In recent years, Poland's off-budget spending has gone from insubstantial amounts to several percentage points' worth of GDP, based on spending tracked by economists and rating agencies.