Words that begin with twin consonant have exception on repeating rule. The word 'trabaho' has a beginning twin consonant 'tr.' "tra" is our first bit. In this situation we are not going to repeat 'tra' but only 'ta'. We remove the second consonant letter to make it easier to pronounce. So the correct is magtatrabaho / nagtatrabaho. Another example the word 'klase' (class). We have twin consonant 'kl' and our first bit is 'kla'. We remove the second consonant letter 'l' and the result is: nagkaklase / magkaklase. More examples: plantsa (flatiron). We removed the second consonant 'l' and becomes: nagpaplantsa / magpaplantsa prutas (fruit). Removed second consonant 'r' and becomes: nagpuprutas/magpuprutas. krisis (crisis) = nagkikrisis / magkikrisis. preno (brake) = nagpepreno / magpepreno. drayb (drive) = nagdadrayb / magdadrayb. However if the word is starting from a twin consonant 'ts' and 'dy', you follow the rule of repeating the whole first bit. Halimbawa: dyip (jeep) = nagdyidyip / magdyidyip tsaa (tea) = nagtsatsaa / magtsatsaa tsokolate (chokolate) = nagtsotsokolate / magtsotsokolate Hope it helped. Goodluck!

Following the grammar rule, “magtratrabaho” would be the correct form. However, in some cases, when we conjugate verbs in the present and future tenses and the first syllable of the root word begins with 2 consonants, we drop the second consonant in the first instance of the repetition. Most likely this is because by doing so the words become easier to pronounce and they sound better too. This usually happens with foreign words that have become part of Filipino as it is very rare in Tagalog to have words that begin with 2 consonants. Almost all of us would choose to say and write “magtatrabaho” (will work) instead of “magtratrabaho”; “magpaplano” (will plan) instead of “magplaplano”. However, we still say “magtsitsinelas” (will wear slippers, from the Spanish “chinela”), “magchecheck-in” (will check in), and more often, “magshashampu” (will shampoo) instead of “magsashampu”.

I know it has been 4 years, but I am dissatisfied with the answers provided,so I will provide my point of view here. The grammar rule, at least to my knowledge, is "CV", meaning ONE consonant (whoch refers to the first CONSONANT) and ONE vowel. In case of trabaho, it would then become "nagTAtrabaho". Now as already mentioned in the previous answers, there are consonant clusters, that when used together, create a new sound. In the case of "dy", the pronunciation is "j" like in "jacket". In the case of "ts" the pronunciation is "ch" like in "China". What I am trying to point out here, is that there are no exceptions I know of when it comes to verbs. The rule applies to all verbs.