Hi I am on the assessment phase of the contribution made Employment and Support Allowance and have not got the outcome from a Work Capability Assessment yet. I also applied for PIP in December 2019 but was not invited to the assessment yet. I came across the information that Contribution-based ESA can be paid with Income-related ESA or Universal Credit. Please advise should I apply or wait for the assessment decision. Thank you.
I am guessing that you are actually receiving New Style ESA which is a Contribution only benefit.
You can claim Universal Credit in addition to the ESA, you may receive more with UC depending on your circumstances, try putting your information into one of the online benefit calculators.