Estimated Tax Payments
Also called: quarterly taxes, estimated taxes, payments on account
Estimated tax payments are quarterly instalments owed by people whose income isn't withheld — the self-employed, investors, landlords. Underpay and penalties accrue as interest from each missed date. The reliable defence is the safe harbour: pay at least 100% of last year's tax (110% at higher incomes) and no penalty applies, however much this year's income turns out to be.