The most broadly accepted homeownership rule: budget 1-2% of the home's value per year for maintenance and minor repairs.

• $250,000 home: $2,500-$5,000/year = $208-$417/month
• $350,000 home: $3,500-$7,000/year = $292-$583/month
• $500,000 home: $5,000-$10,000/year = $417-$833/month

This covers the normal annual expenses that don't make headlines but never stop: roof repairs, caulking and weatherstripping, HVAC filter and service calls, pest control, plumbing minor repairs, gutter cleaning, exterior paint touch-up, appliance repairs, and the hundred small items that every homeowner faces.

The 1% rule understates costs for:
• Older homes (pre-1990): budget 1.5-2% or higher
• Homes with pools: add $2,000-$4,000/year
• Larger homes: economies of scale break down above 3,000+ sq ft

The rule is also lumpy: you may spend $1,200 one year and $15,000 the next when the water heater and dishwasher fail in the same month. The annual budget is the average; cash reserves for the lumpy year are the protection.

Separate from the annual maintenance budget are the capital replacement items that occur on multi-year cycles:

• HVAC system: $6,000-$15,000 every 15-20 years. Florida: more frequent service calls due to year-round use; budget the higher end.
• Roof: $9,000-$25,000+ every 15-30 years depending on material (see the Roof Economics silo). In Florida: may be necessary more frequently and generates insurance implications.
• Water heater: $1,000-$2,500 every 10-15 years.
• Appliances: refrigerator ($800-$2,500), dishwasher ($700-$1,800), washer/dryer ($1,000-$3,000 combined) every 12-20 years.
• Exterior paint: $3,000-$10,000+ every 7-12 years.
• Driveway and walkways: $2,000-$8,000 resurfacing every 15-25 years.

The total capital replacement cost over a 10-year homeownership period: $25,000-$60,000+ for a typical home. Amortized: $2,500-$6,000/year in theoretical reserves. Adding this to the annual 1% maintenance budget produces a more realistic total ownership cost than the mortgage calculator ever shows.

Property tax reassessment: in states with assessment caps (Florida, California, Texas), new buyers are assessed at the purchase price while prior owners enjoy decades of below-market assessments. The prior owner's $3,200/year tax bill on a home you paid $550,000 for may become $5,800/year when the county reassesses at your purchase price. The year-two payment shock is entirely predictable — and entirely missed by buyers who checked the prior owner's tax record instead of calculating from their own purchase price.

Insurance renewal increases: in Florida and California, annual insurance increases of 20-40% are not unusual in high-risk zones. A $4,500 first-year premium may become $6,200 two years later without any changes to the property. This is not in the payment calculator.

HOA special assessments: documented separately in the HOA silo; $5,000-$50,000+ per unit in Florida condos post-Surfside. An annual HOA fee line in the calculator misses this entirely.

The hidden cost summary: on a $350,000 home, the total hidden costs (maintenance 1.5%, major system reserves, insurance increases, and tax reassessment) can add $800-$1,500/month to the "calculator payment" — an amount that surprises almost every first-time buyer.