At present the UK DWP pension is not taxed in the UK.
Mine is! (as I have large SERPS extras).
Just not “at source”:
the tax (a lot!) is collected by deductions (paye) on other income sources.
There is indeed a “similar document” for the U.K. but its contents are markedly different.
Please do not confuse this issue by posting such facts that are totally unrelated to the facts for U.K. taxpayers.