By politics.co.uk staff
The Unite union is pressuring parliament's expenses watchdog to make paternity leave claims unconditional.
At present MPs are allowed to make maternity and paternity leave claims for themselves and their staff under the contingency allowance fund, after the Independent Parliamentary Standards Authority (Ipsa) initially ignored MPs' right to paternity leave completely.
Unite objects to the present arrangements, which Ipsa is empowered to reject at its "sole discretion".
It can do so if the MP "could reasonably have been expected to take any action to avoid the circumstances which gave rise to the expenditure".
Unite's parliamentary branch secretary Louise Haigh said MPs deserved a written guarantee that paternity claims would always be paid.
"Maternity and paternity leave are entitlements and are not subject to Ipsa's discretion," she argued.
"There is also a great deal of ambiguity around what action an MP could reasonably have been expected to take to avoid the need for these payments. We are concerned that Ipsa's approach could deter some MPs from hiring female staff."
The watchdog is set to review MPs' expenses rules this autumn, after a tumultuous few months of the new parliament.
The usually deserted Commons' Westminster Hall debating chamber was packed when MPs chose to debate the new expenses regulator this summer. Many have complained about the unfairness of the present system.
Ipsa's operations director quit in June after being overwhelmed by the stress of the job. The watchdog has advertised for an £80,000-a-year replacement, the BBC reported, seeking a person who would help keep Ipsa "cost-effective".