A person's income for the year is decided on Rosh Hashanah?

This is what the Gemara in ביצה states, כל מזונותיו של אדם קצובין לו בראש השנה. Therefore, according to this, in December there is no reason to work overtime to get a bonus, after all it was decided a few months earlier how much money you will make so your hard work is completely irrelevant.

In fact, the Hirhurim blog a few years ago quoted Rav Feivel Cohen about this subject as follows:

R. Feivel Cohen (author of the Badei Ha-Shulhan) returned from a convention of Agudath Israel of America somewhat upset. It seems that there was a big discussion at the convention about what some were calling a "tuition crisis." R. Cohen pointed out that the Gemara in Beitzah 16a states the following:

All of one's livelihood is determined from Rosh Hashanah through Yom Kippur except for what one spends on Shabbos, on holidays, and one's children's Torah education because [for these three things] if one reduces [the expense] they reduce [one's income] and if one adds [to the expense] they add to one's income.

Clearly, said R. Cohen, there cannot be a tuition crisis. The more you pay for tuition, the more one receives as income to make up for that expense. At least according to the Gemara and "We know what we call people who do not believe what the Gemara says."

So according to R' Cohen there can't be a tuition crisis because the Gemara says that Hashem will pay you back so you can pay any amount in tuition as you will simply make the money back.

While this sounds good in theory, in practice it doesn't work. There is a tuition crisis and most people including Charedim see a link between what they do and the financial results. In fact, the Charedi world is full of quick rich schemes and other illegal ventures. The Jewish Worker has a great post detailing some of these here Fascinating letters in yesterday's Yated.

The Gemara in Rosh Hashana seems to contradict the Gemara in ביצה. The Gemara on 16a states that there are 4 judgement days, on Rosh Hashana people are judged, on Pesach תבואה (which in those days was the equivalent of income) is judged etc. The Ran asks what is going on, if a person is judged on Rosh Hashana, surely that includes a judgement on his תבואה, if so what is the judgement on Pesach? He answers that the judgement on RH is for individuals and the judgement on Pesach is for the nation. The Turei Even asks, how does that answer the question? If everyone in the nation is judged on Rosh Hashana individually then in essence the nation was judged as well so what is judged on Pesach?  He gives the following ingenious answer. He says that on Rosh Hashana a person is judged and given not a specific amount of תבואה, but rather a percentage of the nations תבואה, e.g. 1%. On Pesach the nation is judged and allotted a specific amount of תבואה. Therefore your ultimate income is a combination of your personal judgement (the percentage) and the national judgement. With this he explains a difficult statement of Abaye. Abaye says that if a person sees in the winter months before Pesach that things are going well it is a sign that the judgement of the previous year was good and therefore, he should try to plant and harvest as much as possible before Pesach.  The question is obvious, how can you get more then you were given on Rosh Hashana? With the Turei Even's answer, we can understand this as well. Here is a simple example with numbers. On the Pesach before RH it is nigzar that your country will get 1,000,000 bushels of wheat. On RH it is nigzar that you will get 1% of that. The next Pesach it is nigzar that your country will get only 500,000 bushels of wheat. If you get 50% of your allotment before Pesach and 50% after Pesach you will end up with 0.5% of 1,000,000 which is 5000 and and 0.5% of 500,000 which is 2,500 for a total of 7500. What Abaye is suggesting is that you try to get 70% of your allotment before Pesach and only 30% after. If you do that you end up with 0.7% of 1,000,000 which is 7000 and 0.3% of 500,000 which is 1500 for a grand total of 8500. In other words even though you got the same 1% percent of your country's total in real terms you ended up with an extra 1000 bushels.

Many times, the word תבואה represents not just grain, but parnasa as a whole. If that is the case here then it turns out that a person's income is not fixed in absolute terms on RH. Rather, it is set as a percentage of the total income of the country. Therefore a person could increase their income by doing what Abaye suggested, shifting the distribution around. This could mean that there is justification for a person working harder to get a bonus in the winter, his hishtadlus really does increase his net income and this is not in contradiction to the fact that a person's income is fixed on RH because what is fixed is the percentage not the actual amount.

When I first saw this Turei Even when I was younger, I was blown away by this answer. It was brilliant and so neatly answered the questions. Now I am quite skeptical. Is this really the pshat in the Gemara? Is God really running a crazy scheme like this to provide people parnassa? He allocates percentages to every person in the nation and then an amount to the nation? Really? Does God really give you a way to game the system as Abaye suggested?  When you take a step back and think about how God should/could run the world, this kind of crazy scheme is not what would come to mind.