A war widow's pension is not taxable (see EIM74301).
Sometimes a pension or allowance is not paid or only a reduced
amount is paid because the claimant gets a different benefit, for
example, widowed mother's allowance (see
EIM76177) or widow's pension (see
Where this happens the amount of that other benefit that equals the amount of pension above that would otherwise have been paid, is exempt from income tax (Section 640 ITEPA 2003).