I've probably done 8-10 full contracts total during all my time playing Megamek.
I thought I had a pretty solid grasp on what factors went into determining contract pay.
I just discovered last night that "Base Amount" is NOT entirely determined by (unit rating and) what units you show the employer in your ToE. Nor "Straight Support". "Transportation" surprised me too, though upon reflection it really shouldn't have (mothballed units are efficient bulk Cargo, so cost less to transport - I get it).
I have been setting up for my current campaign's 3rd contract - a Garrison Duty on the Fed-Capellan border that will start in early 3027. I knew I wanted to optimize, at least somewhat, the pay my company received. And I wanted to make an informed decision about how many lances we would be responsible for providing, so I sorted my top 41 units (mostly, but not entirely, mechs) into 01-11, 12-17, 18-23, 24-29, 30-35, and 36-41, by their value, checking the contract pay after filling each of those 6 groups. In the process of monkeying around with this, I noticed numbers were changing, rather substantially, without any change in what was in the ToE. That's when I realized that all those tanks that I had been mothballing over the course of the previous week in preparation for the upcoming travel needed to be brought back out of mothball before I negotiated the contract. How much money am I talking about? At the moment it appears to be about 15 Million C-bills extra just for un-mothballing about 2-3 dozen light tanks. (That's with standard contract based on 5% value, B-rated outfit, 14-month GD contract, 11 units in ToE, 100% straight support, but only 30% transport cost covered, 91 days/5 jumps away.) Going from 95M to 110M is kind of a big deal! Makes me a tiny bit sick to my stomach that I am only just now discovering this after all this time. What other important rules/factors have I been oblivious to? (After all these years, why is there no thread with all the critical insights in one place??)
Obviously, the transportation portion of the increase comes with a bit of an asterisk. I know that we will need to spend time after signing the contract re-mothballing those tanks that we want to keep (some will be sold), or it will end up hurting my outfit more than it helped. All told, I figure my half a month of shenanigans will cost us roughly 250k to 500k in expenses (and perhaps 2-5x that in opportunity cost). A trivial price to pay for an extra 15M!
So I lost all my physical books 2-3 moves back. I can't find anything online (and I've exhausted all the search terms I can think of on these forums). What are the rules for contract pay? I'm less interested in the multipliers for different employers, different time periods, or even different contract types. I am more interested in, what are the BASE formulae for Base Pay, and Straight Support? Is Base Pay even supposed to factor in units not in the ToE?
Mostly-Off-Topic-but-Vaguely-Related piece of advice for players who haven't thought it through:
During a contract, Keep Everything. Sell Nothing. AFTER you negotiate your next contract is the time to sell all those Vedette husks, 25-ton 250-IC engines, ever-growing mountains of MG ammo that you will never be able to expend in battle, etc.