Lots of workers do overtime to supplement low wages. But while you might feel the need to do this to get by, the system of overtime itself helps the bosses keep your wages down.
Other workers, even if their pay is OK, might feel pressured to do overtime to keep the job running and save their workmates from carrying the burden of uncovered duties. But where employers can rely on workers doing overtime, you find that vacancies take longer to be filled. Why should the company hurry up spending money on recruiting, training and kitting out new staff when they can use the existing ones? Even where overtime rates are higher than normal rates, they are cheaper for the employer than hiring a new worker.
Some of us are required by contract to work overtime in situations like emergencies or service disruption. Management can often abuse this by, for example, operating unrealistic timetables or keeping staffing levels close to minimum numbers.
Overtime is time when we could and should be away from work, enjoying time with friends, family and leisure. Those workers with responsibilities outside work eg. kids or adult dependants, are less available for overtime. Fact: wherever overtime exists, women are paid less.
When individual workers go after overtime, we compete with our workmates instead of uniting against the boss. There's an unholy scramble to check what turns are available and nab them before others do - and resentment at others perceived to be getting in first or doing more than their 'fair share'.
Workers end up looking over our shoulders, bitching about workmates - and at the end of the pay period taking home different amounts of money. This makes it harder to unite workers for common demands, such as better pay.
Your boss is still exploiting you even while you think you are getting an extra bit of the cake. Karl Marx explained how during your time at work, you work a little while to pay your own wages, then the rest of the time to make profit for the boss.
So that rest day you worked - maybe a couple of hours went into your pay packet, but the rest went into your boss's fat-cat salary and the company's profits. Voluntary overtime may look like a fair deal between the workers and the employer - but in fact, it is still exploitation.
For all these reasons, we can see that overtime harms the workforce and benefits employers. But it also makes no sense for society in general. It is absurd that some people work long hours and overtime while others are unemployed. It's another example of how irrational a system capitalism is.
A workers' government - one that genuinely represented working-class interests - would bring in legislation to cut working hours and scrap overtime, so creating both work for the jobless and life for the workers.
Marx wrote at length about working hours, stating in 'Capital' that "in its blind unrestrainable passion, its were-wolf hunger for surplus-labour, capital oversteps not only the moral but even the merely physical maximum bounds of the working-day. It usurps the time for growth, development, and healthy maintenance of the body. It steals the time required for the consumption of fresh air and sunlight."
Where overtime is voluntary, remember that you don't have to do it and you don't have to give a reason to refuse.
We don’t make a moralistic demand that individuals must refuse overtime. But collectively, we need to fight to maintain bans on non-emergency overtime where they already exist, and to progressively restrict it elsewhere - with rises in basic pay so workers do not lose out.
That way, workers could not be compelled by financial or other pressure to work overtime when we could be out enjoying ourselves - and the employers could not use overtime, and some people’s over-enthusiasm for doing it, to undermine us.