I am not familiar with the Parliamentary Budget Officer's analysis. According to the analysis we carried out at the time, if only one of the two spouses earns an income, the gains stemming from income splitting are larger. So fiscal costs are higher. If household composition is stable, the cost will be relatively stable over time. If the composition changes and the proportion increases—both spouses earn an income—that cost will decrease, by definition, as both adults will have an income. In that case, income splitting will be less beneficial for them, and the cost will be lower.
What is being said here and what was said at the time is that, based on past trends, women's increased participation in the labour force and the fact that many households have two income earners, the impact should basically decrease over time. We never said anything about the cost being eliminated, but we did talk about a proportional drop.