src/Server.php
public function accountExists($accountId)
    {
        // Handle basic errors such as malformed account IDs
        try {
            $account = $this->getAccount($accountId);
        } catch (\InvalidArgumentException $e) {
            return false;
        }

        // Account ID may be valid but hasn't been funded yet
        if (!$account) return false;

        return $account->getNativeBalanceStroops() != '0';
    }
public function accountExists($accountId)
    {
        // Handle basic errors such as malformed account IDs
        try {
            $account = $this->getAccount($accountId);
        } catch (\InvalidArgumentException $e) {
            return false;
        }

        // Account ID may be valid but hasn't been funded yet
        if (!$account) return false;

        return $account->getNativeBalanceStroops() != '0';
    }
Returns true if the account exists on this server and has been funded

@param $accountId
@return bool
@throws HorizonException
@throws \ErrorException