Does the NATO membership process have negotiable elements? For example, do different members have different terms, or pay different contributions to costs?
Announcing your firm intention to join before negotiating those parts seems like a good way to be paying over the odds forever...
Every country has a requirement to pay 2% of their GDP on defense. However not all countries actually comply. Germany was repeatedly criticized for skimping on their payments. They didn't start contributing 2% until after Russia invaded.
As I understand it, NATO is not a cost-sharing arrangement. Everyone pays for their own defense forces.
Sure, that means if some country were to pay nothing for theirs -- i.e. don't have any -- then the others would have to do all the defending of that country, and so "pay indirectly"... If that country were attacked. That's why NATO agreed that members should spend at least two percent of their GDP on defense, and it is many of them not having got up to that level yet that the USA (especially under Trump) has been complaining about.
But still, that's all within each country's own budget. There are no monetary transfers to and from countries such as "membership fees" or "subsidies" within NATO. (At least not any significant ones that I know of. Maybe some smaller stuff like, Idunno, base rentals or port fees?)
There is about 2.5 billion euros in budget used by the organization directly. This includes people employed directly by the organization, costs related to head headquarter buildings, etc, some command and control infrastructure owned by the organization rather than individual members, some things like deployable radar systems owned by the org directly, plus funding for certain operations that members have agreed to fund via cost sharing, rather than by having any participating members finance their own costs.
Remember, NATO is not just a defensive pact, but also command structure set up to enable the member forces to be utilized as a single cohesive force, rather than just a bunch of allied but disjointed forces. That means communication systems, and setting up unified commands to which portion of member forces can be assigned, making sure equipment and communications systems are intercompatible, etc.
This central funding money is pretty negligible compared to the 2% spending on defense commitment of members. Like the whole central funding would be around 6% of Germany's military budget, but would be fraction of a percent of the US budget. However the central funding is shared amongst all the members. Germany's actual share ends up around 1% of its military budget, UK's actually share is about 0.6% of the UK's budget, and the US share might as well be a rounding error, being my my quick calculations less than a tenth of a percent of the overall budget.
It's certainly not nothing, but is is not like we are talking about super significant portions of countries military budgets.
Announcing your firm intention to join before negotiating those parts seems like a good way to be paying over the odds forever...