No – a director’s fee isn’t needed as you can potentially utilise your personal allowance to offset against income taxed at source when paid by your agency into your company.
The main reasons to process a director’s fee is to utilise your personal tax allowance efficiently (if you have no other employment income or pension income), benefit from corporation tax relief on your director’s fee and ensure that you making adequate credits towards your state pension.
If you are working through your company when captured by IR35 then funds paid into your company are received net of income tax and National Insurance. As a result, it is generally more tax efficient to utilise your personal allowance against this income taxed at source by the feepayer (usually the agency paying your company). In addition, NI credits are still being maintained to your state pension. If you are captured by IR35 for the full year, then your income has already been taxed so there is no further corporation tax liability. Therefore, the provision of a director’s fee as an additional company expense would not provide any further tax relief in the accounting period.