This is a personal set-aside helper for cash-flow planning, not tax advice or a filing. In Manual mode the rate is the number you enter. The Italy · regime forfettario model estimates set-aside as imposta sostitutiva (5% first 5 years / 15%) plus INPS Gestione Separata, applied to gross × coefficiente di redditività — all three values are editable and reflect 2026 rules (€85,000 ceiling). Big caveat: how prop-firm income is classified in Italy is genuinely unsettled — lavoro autonomo (partita IVA, the assumption here), redditi diversi, or capital gains at 26% are all argued depending on the contract and payout structure, and that choice changes everything. The forfettario also has entry requirements and the 5% rate only applies to genuinely new activity. Rates and thresholds change; confirm your real position with a commercialista. Fiscal residence is where you are tax-resident, not wherever you physically are.