Do you get paid for these overtime hours ?

Does this answer your question? Underpaid and overworked, how should I approach my boss?

Where do you live? In some countries (e.g. members of the EU), excessive overtime is illegal, and your employer (not you) could get fined for that. Also, studies have shown that excessive overtime decreases performance, doing excessive overtime for longer periods can actually reduce your productivity compared to just working 40 hours a week.

@JoeStrazzere I believe the project is important to my manager and the company but it's not urgent. It could be ready a month or two later and people would still be happy. But that would probably mean no promotion for me (and possibly others) until the next cycle in 6 months.

“I have a fixed monthly salary which does not depend on the hours worked - I am supposed to work 40hrs/week.” - So your working unpaid overtime, that’s not good, if you continue to work unpaid overtime you will burn yourself out. I am salaried also but I still get overtime if I want it

How are they forbidding overtime if no one is tracking how much time is being worked?

@BSMP Overtime is forbidden on paper. In practice, people work as much as they want, there is great trust in developers that they will not work less than required. I imagine the company secretly hopes that by incentivizing people with bonuses etc., employees will work more than expected - but it's all unofficial and not expected. I think most of us are happy with the system. Everybody is free to decide when and how much they want to work and you will not get a bad rating for not doing overtime.

@HarryJ You should say in which country you are employed. In the US, what you described is standard operating procedure in many high tech companies. By your description of what you do, you would be an exempt employee in the US, which means your employer is exempt from laws regarding overtime. The so-called 40 hour work week is fiction with regard to exempt employees. In other countries your employer's behavior and expectations would be rather illegal.

@JoeStrazzere You know exactly what "it's officially forbidden to do overtime without prior manager approval" means, at least if the OP is an exempt employee in the US. It means paid overtime without prior manager approval is forbidden. Uncompensated overtime is perfectly okay, and in many high tech companies in the US, expecting employees to put in uncompensated overtime is SOP.

@DavidHammen From what OP is saying the company is not asking to work more than 40 hours, this is a choice OP made. IMHO instead of working 80h week and asking us whether they should tell this to their manager, I believe they should simply have told them that the deadlines were slipping and the project is going to take more time and then it would have been the manager's responsibility to, you know, manage the project. If I were a manager I'd prefer someone that identifies issues and immediately tell me rather than someone who tries to hide them with 40+ hrs of overtime

@DavidHammen - You are guessing without evidence. Where does it say this is in the US? If only paid overtime were the issue, why would the OP put "It's officially forbidden to do overtime without prior manager approval." in the con column? I've never worked at a US company where it was "officially forbidden" to work overtime. And I've never worked at a US company where salaried workers could get paid for overtime at all.

@JoeStrazzere That is exactly how multiple companies in the US where I have worked have done things. One could not submit hours for paid overtime unless authorized. One could submit hours for (and was expected to submit hours for) unpaid overtime to ones heart content. At yet other employers, exempt employees were expected to work over 40 hours per week but charge for exactly 40. That is why I asked the OP to specify in which country they worked. It makes a huge difference. Unfortunately, it appears the OP has not returned since asking the question, so the question is essentially unanswerable.

@DavidHammen - you worked at multiple places where salaried workers could get paid for overtime work? I've never encountered one of those. Perhaps we worked in different domains.

@JoeStrazzere When delivery plans and the so-called 40 hour work week have been in conflict, some of my employers have temporarily authorized paid overtime (but straight time, not time and a half) for exempt employees. They had to be careful in doing so lest their exempt employees be recategorized as non-exempt.

Assuming you tell your boss, you should have a clear view of what outcome you are looking for. Are you asking to have responsibilities removed? Are you asking your boss to state priorities and expecting to work less in the future, leaving some work undone? Are you asking for more pay for doing the work? What do you want to come of it?

@ScottishTapWater In the US, the concept of a 40 hour week for exempt employees is a fiction. Meta, Alphabet, companies owned by Musk, and many other high tech companies expect their salaried (aka exempt) employees to work 50 to 60 weeks, minimum, and at crunch time, a whole lot more than that.

@DavidHammen "Land of the Free" indeed. "You are free to work yourself to death for the benefit of people who already have more money than you can dream of". See also: "Reasons why I will never work for Alphabet, Meta or Musk". I wouldn't be able to sleep at night if I knew my people were working hours like that.

@DavidHammen - Okay, sure, if that's the amount that's expected by your employment contract, that's what you are essentially getting paid for. Any more than that, you shouldn't be doing for free whether it's expected or not. The culture won't change and working conditions won't improve as long as people go along with "this is the way it's always been"

@HarryJ If you don't tell him now, he will find out at the last minute when everything falls apart. Judging from what you've written, the most likely outcome of this is that you miss the launch and you and your manager will be (quite correctly) to blame.