Tax Class Optimizer (Married)

Once you are married you may combine your wage tax classes - and this choice decides how much net income lands in your account each month. First, the essential point: the tax class does not change the total tax you owe at year-end. It only shifts who pays how much in advance during the year. Even so, the right choice pays off, because it affects your cash flow and even wage-replacement benefits. The optimizer makes the differences visible.

There are three classic combinations. IV/IV is the standard and fits well when you earn roughly the same - each is taxed on their own and year-end holds few surprises. III/V pays off when one earns considerably more than the other: the higher earner takes class III with low deductions, the other class V with high ones. There is often more net available this way, but the catch comes later.

That catch is the back payment. With III/V too little tax tends to be withheld during the year, so a back payment threatens at the joint assessment - and with it sometimes an obligation to file a return and make advance payments. The optimizer explicitly flags this risk so the tax office does not catch you cold a year later.

The most elegant solution is often the factor method, that is IV with factor. Here the tax office distributes the tax burden fairly during the year according to the ratio of your incomes. Each pays roughly what actually falls on them in the end - this minimizes both back payments and interest-free advances to the state. The optimizer works through this variant too and compares it with the others.

An often underestimated point is the effect on wage-replacement benefits. Parental allowance, unemployment benefit, sick pay and maternity benefit are based on net income. Anyone who switches to a more favourable tax class before such a phase can noticeably raise the benefit. The optimizer considers this link so you choose the tax class not only for monthly net income but also with an eye on planned parental leave.

In the end your specific case counts. The optimizer takes both your gross incomes, works through the permissible combinations and shows you the joint monthly net income per variant plus a note on whether a back payment is likely. That turns a gut decision into a calculation you can follow.

Everything runs in your browser, your income data stays on the device. The optimizer does not replace tax advice or the tax office's binding calculation, but it gives you a solid orientation for the application to switch tax class - free, no account, and without your figures leaving your device.