Better negotiation, market rate, salary history: the explanations for a pay gap that German courts have already rejected

The pay gap that creates legal exposure is not the headline number. It is the part of the gap that remains after you control for role, grade, qualification and working hours. In Germany that residual, the adjusted gender pay gap, stood at 6% in 2025. The unadjusted figure was 16%, but the unadjusted figure is not what an employer is asked to defend. The adjusted gap is.

And here is the problem most HR and reward teams have not yet internalised: the explanations they instinctively offer for that residual are, in many cases, the precise explanations German and EU courts have already ruled out. Better negotiation. Higher market value. What the person earned in their last job. Each of these is a reflex answer. Each has been tested in court. Each has failed.

This matters more now because of one structural change in the EU Pay Transparency Directive (2023/970). Under Article 18, the burden of proof shifts to the employer. When a worker presents facts suggesting unequal pay for equal or equivalent work, it is the employer who must prove the difference is justified by objective, gender-neutral criteria. A weak justification is no longer a debating point. It is a decided case.

Why the justification question is now the one that matters

For two decades, the operative question in a pay equity dispute was whether the worker could prove discrimination. The Directive inverts that. The worker has to establish a prima facie gap, which the new transparency obligations make far easier, and then the employer carries the load.

An unconvincing explanation for a pay gap is not a grey area. Under Article 18, it is a lost case.

The same logic runs through the joint pay assessment in Article 10. Where reporting reveals a gap above 5% in a category of workers doing equal-value work that the employer cannot justify on objective, gender-neutral grounds, the employer must conduct a joint assessment with worker representatives and remediate. "Justify" is the load-bearing word. The whole obligation turns on whether the reasons for the gap hold up.

So the practical question for every employer is narrow and concrete: which reasons actually count? German case law has answered the inverse of that question with unusual clarity. It has named the reasons that do not.

Five justifications German courts have already rejected

The list below is not a theory of what might fail. Each item reflects a decided ruling by the German Federal Labour Court (Bundesarbeitsgericht, BAG) or the European Court of Justice. Treat them as settled.

1. "He negotiated harder."

Negotiation skill is not an objective, gender-neutral criterion for paying one person more than another doing the same work. This is the core holding of BAG 16 February 2023 (8 AZR 450/21), the most important German equal-pay ruling of the decade.

The facts are worth knowing because they are so ordinary. A female field sales representative and a male colleague were both offered the same starting salary of 3,500 euros gross per month. He negotiated his up to 4,500 euros. She did not. The employer argued the difference simply reflected his stronger negotiation. The BAG rejected that. The man and the woman did equal work; the employer could not point to an objective reason for the gap; negotiation skill is not such a reason.

Two people. The same job. The same opening offer of 3,500 euros. He asked for more. That, the court held, is not a reason to pay her less.

2. "That was the market rate."

Market value cannot be invoked as a blanket justification. An employer may not simply assert that a role commanded a higher price when a particular person was hired. To rely on market conditions, the employer has to prove, concretely and for that role at that time, that it faced real recruitment difficulties, and that the higher pay was both necessary and proportionate to overcome them. A dated salary benchmark is not enough.

The BAG made this explicit in the same 2023 ruling. "Market rate" is not a free pass. It is an evidentiary burden, and a heavy one. Most employers who reach for it have neither the contemporaneous documentation of a failed search nor the proportionality analysis the standard requires.

3. "She earned less in her last job."

Salary history is not a legitimate justification for a pay difference. Anchoring a woman's pay to what she previously earned simply imports an earlier, possibly discriminatory, gap into the new role. German courts have not accepted it, and the Directive closes the door from the other side: Article 5(2) prohibits employers from asking applicants about their pay history at all. A reason you are not allowed to ask about cannot be a reason you later rely on.

There is a sharper edge here. Under the Directive's burden-of-proof rule, being paid below the relevant median is itself an indication that shifts the onus onto the employer. "Lower previous salary" is not a defence to that. It is an admission that the gap was inherited and never corrected.

4. "Part-timers are treated differently as a matter of policy."

Disadvantaging part-time staff as a class is presumptively indirect discrimination against women, because women hold the large majority of part-time roles. A blanket rule, for example paying an overtime premium only above the full-time threshold, is not objectively justified simply because it is the policy. The BAG has held this in a line of cases stretching from 26 February 1992 (5 AZR 225/91) to 19 December 2018 (10 AZR 231/18). Differential treatment of part-timers needs a concrete, role-specific, objective reason. "That is how we have always run it" is not one.

5. "She was on maternity protection."

A woman on statutory maternity protection (Mutterschutz) may not be placed in a worse pay position than her colleagues because of that protected absence. The European Court of Justice settled this in C-333/97 (21 October 1999). Maternity protection is a legally protected status, not a performance signal, and it cannot be used, directly or by omission from a pay round, to justify a lower position.

What does count as objective justification

The case law is not saying that every pay difference between two people doing equal work is unlawful. It is saying that the reason for the difference has to be objective, gender-neutral, and capable of proof. That standard is demanding, but it is not mysterious.

Factors that can justify a difference, when they are real and documented, include relevant professional experience, the qualifications a role genuinely requires, and measured, audited performance. The Directive itself points to criteria such as skills, effort, responsibility and working conditions for valuing the work. The distinction is simple: a legitimate factor describes the job or the demonstrable capability the person brings to it. An illegitimate factor describes how the deal was struck or where the person came from.

A legitimate reason describes the job. An illegitimate one describes the negotiation. Courts can tell the difference, and so can a worker representative.

Performance carries a caveat worth stating plainly. If you use a performance rating to justify a pay difference, the rating itself has to be auditable for gender neutrality. A subjective rating that happens to track gender does not launder a gap; it relocates it.

What employers should do now

The exposure here is not abstract, and the remedy is procedural. Four steps move a company from reflex justifications to defensible ones.

1. Find your adjusted gap before anyone else does. The unadjusted number tells you little. Run the analysis that isolates the residual gap within groups of workers doing equal-value work. That residual is what you will have to justify, so you need to see it first.
2. Audit your existing justifications against the rejected list. Pull the reasons currently recorded for outlier pay decisions. Anywhere the rationale is "negotiated", "market", "prior salary", or "part-time policy", treat it as a gap with no valid explanation until proven otherwise. Under Article 18, that is how a court will treat it too.
3. Document the legitimate factors properly. Where a difference rests on experience, qualification or performance, record it at the point of decision, in gender-neutral terms, and apply the same logic to every comparable employee. A justification invented after a claim is filed is worth little.
4. Bring worker representatives into the methodology, not just the result. The Article 10 joint assessment is a process with a defined role for worker representatives. Agreeing the evaluation criteria before the first report exposes a gap reduces the risk of a dispute about the reasons later.

The gap is not the liability. The explanation is.

A residual pay gap, on its own, is a fact about a pay structure. It becomes a liability at the moment an employer offers a reason for it that the law has already rejected. German courts have spent years naming those reasons, and the EU Directive has now placed the burden of disproof on the employer who relies on them.

The companies that come through this well will not be the ones with no gap. They will be the ones who can explain the gap they have in terms a court, and a worker representative, will accept. That is a documentation problem before it is a pay problem, and it is solvable now, while the reasons are still being recorded rather than litigated.