Not yet a year into the new regime for MPs' expenses, and already it is being tweaked in their favour. This, at least, is how the changes announced yesterday are likely to be seen by many voters.

The accommodation and travel allowances for partners and children are being extended to older children; more MPs will be able to reclaim hotel costs; staff costs are being increased, and MPs will be able to use their payment cards for more than was allowed under the first version of the new rules.

It is possible to understand the rationale for all these measures individually. Reimbursing more costs for children's accommodation and travel relaxes restrictions that were widely seen as inconducive to family life. Permitting wider use of the payment card is a response to those who found themselves seriously out of pocket at the start of the new Parliament. Altogether, as Sir Ian Kennedy, the chairman of the Independent Parliamentary Standards Authority says, the additional cost is small compared with the £18m already saved.

All that accepted, however, it is hard to escape the impression that MPs have used their considerable lobbying skills in their own interests and that Sir Ian has buckled, even a little, under the pressure. Justifying his decision, he said there had always been an intention to review the scheme – if so, why was there no review timetable? – and he would present a figure for the cost of the new scheme to the requisite parliamentary committee on 4 April. Taxpayers – who are, after all, footing the bill – can legitimately complain that standards of transparency and accountability leave something to be desired.

MPs were never going to like having their spending wings clipped, even as most of them recognised the damage done by the expenses scandal. But it was, and is, crucial that the new regulatory body command public confidence. When it started work, there were doubts about how rigorous it would be; there will be a few more now.