Roughly speaking and assuming that your husband earns at least €41,800 then his take-home pay will increase by €4,350 per year. This is calculated as follows:
Increase in 20% band = €9,000 x 21% = €1,890
Transfer of married credit = €1,650
Home Carers Credit = €810
Total = €4,350
Why would the 20% band increase when they are going from a dual income to a single income family....would it not contract ?
The OP's husband's 20% band will increase by up to €9,000 per year as this is the maximum of unused 20% band that can be transferred between spouses. The remainder of the OP's 20% band is lost, as is her PAYE credit which also cannot be transferred (although if she receives taxable Social Welfare payment, then the PAYE credit would normally cover any potential PAYE on this income).
So, assuming that the husband earns at least €41,800, there is now €9,000 of his salary which is taxed at the 20% rate instead of the 41% rate, which is a saving of €1,890 (€9,000 x 21%)
I was specifically speaking about the husband's salary ONLY and I assumed that the OP currently has all of her tax credits.
You are correct about the tax system favouring dual-income couples.
The OP is looking for the impact in her husband's take-home pay as I think we safely assume that her own take-home pay will drop to ZERO if she gives up work.
You are incorrect in assuming that her husband's 20% band would decrease as the max that any one person can earn at the 20% band is €41,800. Her husband CANNOT earn €64,000 at the 20% rate because the OP cannot transfer any more than €9,000 of her own 20% band to her spouse.
Exactly right.
As they are currently a dual income (married) couple they would/should be receiving this relief. By going to a single income couple they lose this dual income status and the husband's income is taxed at 41800 @ 20% and 41% thereafter.