1. Why this isn't just paperwork
The tax regime you choose (or default into when you open your RUC) determines which receipts you can issue, how your Impuesto a la Renta gets calculated, and how heavy your filing load is. It isn't a box you check once and forget — a business that grows without reviewing its regime in time can end up overpaying, or worse, fall outside a regime without realizing it and create contingencies as a result.
Peru has four regimes for business Impuesto a la Renta: NRUS, RER, RMT, and the Régimen General. They go from lower to higher complexity, and also from lower to higher growth ceiling.
2. NRUS: the simplest regime, with the most restrictions
The Nuevo Régimen Único Simplificado is built for individuals with small businesses — not for legal entities. You pay a fixed monthly fee based on your category (which depends on your income and purchases for the month), and that fee already covers both IGV and Renta: neither one has to be calculated or filed separately.
NRUS's most important restriction is the type of receipt you can issue:
- Only boletas de venta and tickets — never facturas.
- If your customer needs crédito fiscal (that is, needs a factura to deduct IGV on their own return), NRUS won't work for selling to them.
You're also excluded from NRUS if you exceed the regime's annual income or purchase caps, if you have more than one establishment that doesn't meet certain conditions, or if your activity is expressly excluded (for example, services rendered under cuarta categoría, or certain foreign-trade activities).
3. RER: special Renta regime
The Régimen Especial de Renta already lets you issue facturas, boletas, and any type of receipt. You pay IGV the same as any other regime (18% with crédito fiscal), and for Renta you pay a flat rate of 1.5% of your monthly net income — there's no profit to calculate, and no annual return with complex adjustments.
In exchange for that simplicity, RER has annual income and purchase caps, and it expressly excludes some activities: construction, heavy cargo transport, notaries, and some professional services, among others. If your activity is on that exclusion list, RER isn't an option even if you meet the income caps.
4. RMT: the regime built for MYPE
The Régimen MYPE Tributario is the middle ground: it has no purchase cap, and the annual net income cap is 1,700 UIT. The Renta rate is progressive — up to a certain bracket of annual profit you pay 10%, and the excess pays the general rate (29.5%).
The monthly pagos a cuenta are also lighter as long as your annual net income doesn't exceed 300 UIT: you pay 1% of the month's net income. If you exceed that, you switch to calculating the pago a cuenta the same way as Régimen General (coeficiente or 1.5%, whichever is higher — we cover it in detail in another article).
5. Régimen General: no limits, more obligations
The Régimen General has no income or purchase cap — it's the only regime with no growth ceiling. The Renta rate is fixed at 29.5% of profit, and the monthly pagos a cuenta are calculated by comparing coeficiente against 1.5% (whichever is higher).
It's also the regime with the most formal obligations: full accounting (Libro Diario, Libro Mayor, and the rest of the ledgers depending on your income volume), without the simplifications that NRUS, RER, and RMT get.
6. How to switch regimes
Moving from a "lower" regime to a "higher" one (for example, from NRUS to RER, RMT, or Régimen General) can be done in any month of the year — you simply file that month under the new regime's rules. Moving from RER to RMT or Régimen General is also possible at any time.
Going back to a "lower" regime (for example, from RMT or Régimen General back to RER) generally can only be done at the start of the following fiscal year, with its own rules depending on which regime you're coming from — it isn't something you can decide mid-year without more.
7. How factsimil handles it
factsimil issues receipts for all four regimes — it doesn't change how you invoice depending on which one you're under. Where the regime does matter is in Accounting and PLE: if you're under RMT or Régimen General, the PCGE chart of accounts, the Libro Diario, and the Libro Mayor are already built on top of the same invoices you issue, with no need to reconcile two systems.
You can create a free account regardless of your current regime, or check the plans if you also need the full accounting module.