Current rules for lenient deductions from pension benefits payable between early retirement and normal retirement pension

This is the best I can suggest without more context.

Efterløn is a benefit paid to people who retire before reaching the normal retiring age. It was introduced in a period of high unemployment, originally for those over 60 who were unlikely to find new jobs because of their age, often combined with outdated qualifications. The age has since been raised, and retiring age is also being raised - it was then 65, and is now 66.5 years.

People receiving efterløn were then exempted from hopeless job applications and looking for work, or being chased around in ´activation´ schemes that were unlikely to succeed in getting them back into real jobs.
I do not know the present rules, but there were quite fierce deductions in the benefit if anyone worked part time or found a seasonal job, even for just a few weeks, after they had started receiving efterløn.

In fact the deductions were milder after they passed the normal pension age, if they worked while qualified for the normal ´folkepension´.

Now the situation is completely different - in theory everyone is encouraged to continue working as long as possible, but the deductions in benefits or pensions discourage some!

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Note added at 1 day 4 hrs (2021-12-02 22:40:39 GMT)
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As Ice Scream points out, this is not tax relief, but a deduction from the benefit itself. The tax on the benefit would be reduced accordingly, but any earnings or other income (the reason for the deduction) would be taxed instead, so there would be absolutely no tax advantage.