Institutions facing investigation in the independent abuse inquiry are set to be identified.
Justice Lowell Goddard, who is leading the probe, will make a statement on its progress later.
It is understood the New Zealand judge is expected to name a number of institutions that will be examined.
The chairwoman will announce investigations which "form the first phase" of its "substantive work".
Since the inquiry formally opened in July, much of the work has been devoted to the research project phase, in which relevant material has been gathered and analysed.
Earlier this month the truth project started, in which child abuse victims gave testimony about their experiences in private sessions.
The probe was set up last year following claims of a high-level cover up of abuse and has been beset by delays following the resignations of two previous chairwomen.
It will be Britain's largest ever public inquiry and is expected to take up to five years and cost tens of millions of pounds.
In her opening statement earlier this year, Justice Goddard said it will travel from from the "corridors of power" in Westminster to the poorest parts of the country to uncover the true scale of child sex abuse.
All strands of public life in England and Wales are expected to come under the spotlight - including politics, children's homes, hospitals, GPs' surgeries, schools, churches, charities, local authorities, the NHS, the BBC and the armed forces.