Do I need to keep the full £50,000 in the Savings Pot?

No — you’ll still qualify for the Welcome Boost even if you keep less than £50,000 in your Savings Pot. However, the boost only applies to the money you hold in the Savings Pot. 

For example, if you kept £45,000 in your Savings Pot and £5,000 in your Primary Wallet, you would still qualify for the boost, but you’d only earn boosted interest on the £45,000 in the Savings Pot.