Would Texas need a federal-style income tax to replace lost services?

No. The arithmetic is the whole answer. Texas already raises enough, without a personal income tax, to cover the full cost of an independent Texas government. There is no funding hole that a new tax would have to fill.

Start with the gap that is supposed to require it

The fear behind this question is that independence opens a hole in the budget, and only a federal-style income tax could close it. So look at whether the hole exists. Texans pay about $453 billion a year to Washington and Austin combined. Governing Texas, with the entire federal footprint folded in, costs about $295 billion a year. The revenue already exceeds the cost. There is no gap to close, so there is nothing for an income tax to fill.

The fair, conservative version still holds

Be rigorous about it. Take Social Security and Medicare off the cost side and, to be fair, take the payroll taxes that fund them off the revenue side. The margin narrows toward break-even. Even then, Texas funds 100 percent of its own government on the taxes it already collects. That is self-sufficiency, not a claim of some giant surplus, and it is true with no income tax anywhere in the picture.

Texas already proves the model works

Texas runs the 8th-largest economy on Earth today without a personal income tax. The sales tax carries most of the load, with the franchise tax, severance taxes on oil and gas, motor-fuels and motor-vehicle taxes, and fees doing the rest. This is not a theory about whether a no-income-tax economy can fund a modern government. It is the everyday reality of the second-most-populous state in America. Independence keeps that model, it does not abandon it.

The new costs are small and largely self-funding

An independent Texas would take on a handful of functions Washington runs from outside the state: a central bank, a foreign ministry, a customs and tax service, and aviation, drug, financial, and communications regulators. The genuinely new recurring bill for all of it runs about $5 to $15 billion a year, one to three percent of Texas revenue, and a good share pays for itself. A central bank is funded by seigniorage, not taxes. The financial, drug, aviation, and communications regulators run mostly on fees, the way their counterparts do in Australia, Canada, and Ireland. None of that calls for a new income tax.

An income tax would defeat the purpose

There is a deeper reason this will not happen. The no-income-tax model is one of the main reasons Texas attracts people and capital in the first place, a net 130,000 new residents a year and more corporate relocations than any state in the country. Replacing that advantage with a federal-style income tax would throw away one of independent Texas's greatest assets. The arithmetic does not require it, and the strategy argues hard against it.

The bottom line

There are no "lost services" to replace, because Texans already fund their government with margin and without an income tax. The model that built the eighth-largest economy on Earth is the model an independent Texas keeps.