Perfective partners: пиша → напиша

The Bulgarian dictionary form is the 1st person singular present, and most verbs have a perfective partner. There are three ways to form it:

• Prefix: пиша → напиша, чета → прочета, ям → изям, каня → поканя, готвя → сготвя
• Shorter stem (the imperfective is longer, often with -ва-): купувам → купя, давам → дам, започвам → започна
• Different stem: казвам → кажа, идвам → дойда, намирам → намеря

A perfective present never stands alone for 'now'. It comes only after да, ще, ако, когато, щом or нека: Искам да напиша писмото (I want to write the letter). Ако изям цялата торта... (If I eat the whole cake...). In every sentence here the act happens once and is completed, so write the perfective.