Can I make additional contributions to my SIPP after starting drawdown?

Yes, you can make further pension contributions if you are under age 75.

Once you have flexibly accessed your pension benefits you are only be able to contribute up to £4,000 to all money purchase pensions each year, including your AJ Bell Youinvest SIPP. Additionally, it is not possible to make use of any unused contribution allowance from previous tax years to increase this amount.