When you first turn on the power in a capacitive circuit, the capacitor acts like a short circuit. Current rushes in at maximum rate, then gradually decreases as the capacitor charges.
While this is happening, the voltage across the capacitor slowly rises, from zero to max. At full charge, the capacitor acts like an open circuit. Current is zero and voltage is at its maximum.
So I can be said that voltage lags the current by 90′