...
The contractor tax details must be recorded on the payee record before the payee record can be saved.
Once defined, a payee's contractor tax details can be modified if necessary so long as the payee is not currently included in an open pay batch.
However, once the payee has been paid (included in a closed pay batch) their contractor tax details, with the exception of their business address details, are locked down for the corresponding payee details validity period and cannot be modified for that period. If you need to modify a payee's contractor tax details after the payee has been paid in one or more pay batches, you must create a new payee details validity period.
...