On 04 May 2020, HMRC announced that people who were unable to work their normal hours due to being furloughed would receive Tax Credits as usual. This will be based on hours normally worked. HMRC’s quote is as follows:
These customers do not need to contact HMRC about this change. We will treat customers as working their normal hours until the Job Retention Scheme and Self-Employment Income Support Scheme close, even if they are not using either scheme.
The number of normal hours worked (RTI field 54) does not need to be amended if the employee is furloughed and working reduced hours (or no hours) in the pay period.
This is good news.
It seems from the announcement that even if the hours were amended, HMRC would look at normal hours anyway.