This was a decline of 0.5% from Q1, which accumulated £420.7m, and a drop of 7.6% compared to the Q2 2020-21 period.
The funds come from sales of games from the National Lottery, along with supplemented unclaimed prizes and interest on balance funds.
The funds for good causes are held in the National Lottery Distribution Fund.
The Gambling Commission explained the slight dip in funds as being down to two instances, the first being a decrease in instant win products such as scratch cards and interactive win games. The second factor was the existence of two unclaimed prizes, leading to total unclaimed funds holding steady.
The National Lottery has raised over £43bn for good causes since its launch in November 1994.
During the Q2 period, the National Lottery delayed the selection of the winner of its tender process, which was launched in August 2020.
The tender process will decide who receives the fourth National Lottery licence in the UK.
Last month, the regulator then revealed that four companies have applied for the licence- Sazka, Sugal & Damani and Sisal have all expressed their interest in bidding, while current licensee Camelot – which said it had committed early parts of the application but did not reveal whether it had bid – had its licence extended until 2024.