minimum savings to stay in Spain

No official minimum figure has been published, but you need to demonstrate you have enough to support you and your family. Unofficial sources have quoted a figure of 6000 ish per year or be able to show 6000 in a bank account, not sure if this is EUR or GBP. You will also need to have Health Insurance for all your family, you won't get state health care but should be able to send your son to state school if you have a official rental contract and go on the electrol role

By staying for 12 months and intending to stay for 12 months you will become a Spanish resident and therefore need to fill up the EX18 form for the EU citizens register rather than the EX15 which only gives you a NIE number 

Surely even asking this question implies that the OP is not sure that they are in a financially viable position to move to Spain, particularly with no job and a 10 year old child to support. But having said that if the OP is confident that they have sufficient funds to house and feed the two of them short term, who am I to be holier than thou?

Many a person has taken a step onto uncertain ground and come out unscathed, I can't answer any of the questions, but unreservedly wish the OP good fortune.     

Here is a official link from the government showing the ex18 form in English (not valid as an application)

The ex15 form is what non residents would use (holiday home owners etc) who need to make financial transactions in Spain but are not here for more than 183 days a year

As Team GB said, no official figure but you may have to prove you can support yourself and your family plus have private or public funded (from your home country) healthcare. Even having a large enough (more than £6000) credit card limit is sufficient to prove you have access to sufficient funds. Healthcare would be the problem as only those under 18, over pensionable age or registered disabled get that. There wouldn't be that many people settling here if the required savings was 30k. (My husband speaks Spanish and has accompanied several neighbours to get residency. Whilst they have had to show proof of healthcare, none have been asked for proof of income but they do own property here).

Schools are all in Spanish so if you think a 10 year old could absorb Spanish in his first year it would work though I would think very carefully about that. You also have to pay for school books etc.

EX15 is the application for an NIE number and you would have to apply to go on the foreign national (commonly called residencia) within 3 months. EX18 gets NIE and residency or non-residency certificates.

I would think very carefully about this especially for the impact on your child's schooling. Most British kids are put into a lower class to catch up with the Spanish system and language.

Axti 101

the amount is 600 euros  per month income and/ or 6000 each adult in a Spanish bank

you will be tax resident in Spain and pay tax on all your income wherever it comes from, including savings interest even on UK tax free isas.

you will have to prove you have private Spanish health cover until you are legally employed with a contract, or if not for 1 year till you can pay 60 euros per month each adult into the Spanish NHS

if you have existing medical conditions, private insurers won't cover them.

when you are under the Spanish NHS all conditions will be covered,

You will pay for prescriptions  

Suggested amount. EU rules state the country cannot set a limit but it is a suggested amount.

And 6,000 each in a Spanish bank? Where did that come from?  I've lived here years and wouldn't keep 12 grand in a Spanish bank. It's access to funds so you could have an account or a credit balance anywhere.

Mind you, an income of 600 euro a month would be quite difficult, if not impossible, to exist on here. I know it's cheap but not that cheap. Alright if you've got family to live with and no rent or bills to pay, I suppose.