If you wait until you receive a letter from the DWP and your new Universal Credit payments are going to be less than what you currently get on Tax Credits, then you’ll be awarded "transitional protection" which is an extra amount which tops up your Universal Credit to bridge any shortfall.
But it is important to know that Tax Credits will stop from the day you put in a claim for Universal Credit - and you'll have to wait five weeks for your first Universal Credit payment to arrive.
The DWP has been sending letters to everyone claiming Tax Credits, giving them a three-month deadline to start claiming Universal Credit.
Some legacy benefits - including Housing Benefit, Income Support, Income-related ESA and Income-based JSA - will "run on" for two weeks after you put in your claim for Universal Credit.
If you think you will be better off, get advice first before switching to Universal Credit - as once you make the move, you can’t go back to your old benefits.