How to appeal
If your employer decides you are not entitled to SSP and you do not agree with this, the employer must give you the reasons for its decision in writing. You can appeal against this to the HMRC within six months of the refusal to pay. You will need to state the period for which you are claiming SSP and your employer’s grounds for refusing to pay. Your local Jobcentre will have details on how to make an appeal. You can write directly to the HMRC to pursue your claim if your employer refuses to provide you with anything in writing.
A claim for unpaid sick pay (SSP or contractual) should be brought in the Employment Tribunal as a claim for unlawful deduction of wages or breach of contract.