Picked up at a library book sale.

From the back cover:

Mary Gilmour is struggling to cope. Her job is part time but housework is full time, leaving no time at all for her two young sons - let alone herself. For Mary, there is only one thing standing between her and a life of organised contentment: her husband, Joel.

Since star charts worked wonders improving their children's behaviour, she commits her unknowing husband to the same fate. A spreadsheet, detailing every dirty tissue, every lost sock, and every wet towel on the bed.

Joel has six months to prove his good behaviour outweighs the bad. Or else...

On the bookshelf in the ticket office