What is the ruling on raising the sale price by 300% when submitting invoices to a government office that collects 10% of the project value, with the government office being aware of the increase and remaining silent?

That is impermissible due to the deception, fraud, and bribery involved. The Prophet, peace and blessings be upon him, said: "Whoever cheats is not one of us," and "Indeed, there are men who delve into the wealth of Allah without right, and for them is the Fire on the Day of Resurrection."