Planning long term stay in Spain - 9 to 12 months

I don’t think there are many folks here with experience getting Spanish residency. However, there are a few groups on Facebook that discuss this extensively. Look for “Americans in Spain” or “American expats in Spain” in FB groups. If you scroll and read there you’ll learn loads well before even asking any questions.

Taxes are an issue. Income taxes and Spain’s global wealth tax. If your plan is only for one year, the easiest thing would be to arrive after July 3rd and leave before July 1st the next year, never spending 183 days of a given year in the country. This will prevent you from becoming a tax resident at all.

And note that while you’d have residency in Spain, you’d still be technically subject to 90/180 for the rest of the Schengen zone, like any other American tourist. (Though it’s harder for authorities to track, and is less enforced.)

Spain will charge income tax against US citizens who have become tax residents of Spain by living there for 183 or more days. The Spanish have their eyes on this issue, look at the current uproar over the criminal tax evasion trial for Shakira. This applies even to retirees whose only income source is passive income derived from the US (such as pension, Social Security, 401s). You can look up the Spain - US tax treaty to confirm the current details but that is my understanding that Spain will tax based on global income regardless of source.

I would recommend Portugal (where there is a ten-year exemption for new legal residents who are US residents) or France (where they do not assess income tax on US legal residents who are retired with sole source of income from retirement income sources in the US and not earning any income from working in France). The key is checking out the tax treaties that exist between the US and the country you are interested in, the treaties are supposed to help avoid or lighten the load of double-taxation (since the US charges income tax on all US citizens regardless if they are overseas and retired). As a correction to the other poster, my understanding is that once you have acquired legal residency in any one EU country then you are no long subject to the 90/180 visa-free Schengen time restrictions (i.e. EU states provide reciprocity to EU legal residents regardless of which country) because you are now legally present in a EU country based on a formally approved visa as opposed to a visa-free tourist.

David is mostly correct that Spain taxes income from almost any source (any kind of government pension is exempt, including, say, teacher's pensions). His mention of being liable for taxes when being there more than 183 days misses the nuance of those days being within a single tax/fiscal year, as I'd mentioned. US citizens are liable for US taxes on worldwide income, wherever they live in the world. The bilateral tax treaty does prevent double taxation—the oversimplification is that you calculate both returns and only pay the higher liability.

Spain is certainly not the most tax-efficient solution for expatriating, and for one year Portugal may be better. But when comparing total liabilities and services received for the cost, it compares favorably to the US for establishing longer-term residency.

The Schengen 90/180 issue was mentioned to me as an aside by the Spanish tax attorney I've consulted with regarding my own, long-term move that I'm planning. Admittedly, he is not an immigration attorney, but his firm specializes in ex-pat services.

You need to ask an accountant about tax advantages and liabilities. From what I understand, if you divide your time from July to the following June, keep both years under 183 days for Spanish taxes, but over 350 days for US taxes, you will not need to pay in Spain ( note that you may need to file or write a letter stating you Spain is secondary). OTOH you will benefit from certain US tax advantages from being overseas for nearly a year. This is based on the experiences of US faculty spending academic years abroad.

You should be able to find the US Spanish tax treaty online or through a private FB group for expats.

It's the US tax advantages that could be harder to find.

This comes up in the three expat FB groups I belong to for France. In our case, the procedure is so simple that everyone says not to waste the money. We have several international accountants and legal specialists in the FB groups.

I suggest you join the Spain FB group/s for expats, research and ask the questions. That way you'll get answers from people who have done what you are planning to do, some with professional expertise. Then you will know if you need to hire an attorney.

Only one person who has answered here has lived in Spain. Most of us aren't qualified to tell you if you need an attorney or not.

Thanks to all who have provided advice. When I researched the NLV it was not clear to me that the cut off point of 183 days was per fiscal year, not just 183 days from the start of the visa. This is a game changer because we already planned to split the time over two calendar years. We will also consider looking at Portugal as an option. From our base in Spain, we will be planning trips of 2 to 3 weeks in other EU countries so that should not be an issue with a US passport.

I've purposely avoided joining Facebook but may reconsider if it is a good resource for planning.