Claiming certain tax credits can impact on other benefits received by a claimant. HMRC have provided guidance which outlines when and how benefits such as Council Tax Benefit, Housing Benefit, Income Support, income-based Jobseeker's Allowance, income-related Employment and Support Allowance and Pension Credit are taken into account when means testing entitlements to benefits.

HMRC recommends contacting the benefit office and ask them to check how tax credits could affect a particular benefit payment before a claim to tax credits is made.

The extracted HMRC note is here.